diff --git a/src/main/java/com/spring/modules/quote/service/impl/QuoteDetailBomTreeServiceImpl.java b/src/main/java/com/spring/modules/quote/service/impl/QuoteDetailBomTreeServiceImpl.java
index 809011e0..e6e0410a 100644
--- a/src/main/java/com/spring/modules/quote/service/impl/QuoteDetailBomTreeServiceImpl.java
+++ b/src/main/java/com/spring/modules/quote/service/impl/QuoteDetailBomTreeServiceImpl.java
@@ -552,9 +552,18 @@ public class QuoteDetailBomTreeServiceImpl extends ServiceImpl<QuoteDetailBomTre
     @Override
     public List<QuoteDetailBomTree> queryDetailBomTree(QuoteDetail detail) {
         List<QuoteDetailBomTree> list = baseMapper.queryDetailBomTree(detail);
+        long rootCount = list.stream()
+                .filter(node -> Objects.isNull(node.getParentId()) || Long.valueOf(0L).equals(node.getParentId()))
+                .count();
+        if (rootCount > 1) {
+            log.warn("[BOM_TREE] QuoteDetailId={} has {} root nodes, fallback to latest root node by id.",
+                    detail.getId(), rootCount);
+        }
         QuoteDetailBomTree quoteDetailBomTree = buildTree(list);
         List<QuoteDetailBomTree> treeList = new ArrayList<>();
         if (Objects.nonNull(quoteDetailBomTree)) {
+            log.info("[BOM_TREE] QuoteDetailId={} selected root treeId={} for tree display/query.",
+                    detail.getId(), quoteDetailBomTree.getId());
             treeList.add(quoteDetailBomTree);
         }
         return treeList;
@@ -919,13 +928,12 @@ public class QuoteDetailBomTreeServiceImpl extends ServiceImpl<QuoteDetailBomTre
     }
 
     private QuoteDetailBomTree buildTree(List<QuoteDetailBomTree> nodes) {
-        QuoteDetailBomTree root = null;
-        for (QuoteDetailBomTree node : nodes) {
-            if (node.getParentId() == null || node.getParentId() == 0) {
-                root = node;
-                root.addChildren(nodes);
-                break;
-            }
+        QuoteDetailBomTree root = nodes.stream()
+                .filter(node -> Objects.isNull(node.getParentId()) || Long.valueOf(0L).equals(node.getParentId()))
+                .max(Comparator.comparing(QuoteDetailBomTree::getId, Comparator.nullsLast(Long::compareTo)))
+                .orElse(null);
+        if (Objects.nonNull(root)) {
+            root.addChildren(nodes);
         }
         return root;
     }
diff --git a/src/main/java/com/spring/modules/quote/service/impl/QuoteDetailServiceImpl.java b/src/main/java/com/spring/modules/quote/service/impl/QuoteDetailServiceImpl.java
index b1ac173f..a2a8b97f 100644
--- a/src/main/java/com/spring/modules/quote/service/impl/QuoteDetailServiceImpl.java
+++ b/src/main/java/com/spring/modules/quote/service/impl/QuoteDetailServiceImpl.java
@@ -233,6 +233,11 @@ public class QuoteDetailServiceImpl extends ServiceImpl<QuoteDetailMapper, Quote
                 .orderByDesc(QuoteDetailBomTree::getId)
                 .list();
         QuoteDetailBomTree one = roots.isEmpty() ? null : roots.get(0);
+        Long rootTreeId = Objects.nonNull(one) ? one.getId() : null;
+        if (roots.size() > 1) {
+            log.warn("[COST_CALC] QuoteDetailId={} has {} root nodes, use latest root treeId={} for calculation.",
+                    quoteDetail.getId(), roots.size(), rootTreeId);
+        }
 
         // 3、工艺成本
         BigDecimal labourCost = BigDecimal.ZERO;// 人工成本
@@ -243,11 +248,22 @@ public class QuoteDetailServiceImpl extends ServiceImpl<QuoteDetailMapper, Quote
         BigDecimal unitQuotePrice = BigDecimal.ZERO;
 
         // 获取BomTree 根据层级倒序
-        List<QuoteDetailBomTree> list = quoteDetailBomTreeService.lambdaQuery()
+        List<QuoteDetailBomTree> allTreeNodes = quoteDetailBomTreeService.lambdaQuery()
                 .eq(QuoteDetailBomTree::getQuoteDetailId, quoteDetail.getId())
                 .orderByDesc(QuoteDetailBomTree::getLevel)
                 .orderByDesc(QuoteDetailBomTree::getId)
                 .list();
+        List<QuoteDetailBomTree> list = new ArrayList<>();
+        if (Objects.nonNull(rootTreeId)) {
+            List<Long> subtreeTreeIds = quoteDetailBomTreeService.getAllChildIds(quoteDetail, rootTreeId);
+            subtreeTreeIds.add(rootTreeId);
+            Set<Long> subtreeTreeIdSet = new HashSet<>(subtreeTreeIds);
+            list = allTreeNodes.stream()
+                    .filter(node -> subtreeTreeIdSet.contains(node.getId()))
+                    .collect(Collectors.toList());
+            log.info("[COST_CALC] Root treeId={} selected, subtree node count={}, all node count={}",
+                    rootTreeId, list.size(), allTreeNodes.size());
+        }
         
         log.info("[COST_CALC] [PERF_LOG] Fetching {} BomTree nodes took {} ms", list.size(), (System.currentTimeMillis() - perfTreeStartTime));
 
@@ -275,7 +291,6 @@ public class QuoteDetailServiceImpl extends ServiceImpl<QuoteDetailMapper, Quote
             Map<Long,List<QuoteDetailBom>> bomMap = bomList.stream().collect(Collectors.groupingBy(QuoteDetailBom::getTreeId));
             log.info("[COST_CALC] [PERF_LOG] Fetching and grouping {} BOM component records took {} ms", bomList.size(), (System.currentTimeMillis() - perfBomStartTime));
 
-            long treeId = 0;
             int nodeIndex = 0;
             
             long perfConvolutionStartTime = System.currentTimeMillis();
@@ -288,7 +303,6 @@ public class QuoteDetailServiceImpl extends ServiceImpl<QuoteDetailMapper, Quote
                         nodeIndex, list.size(), bomTree.getPartNo(), bomTree.getLevel(), bomTree.getId(), bomTree.getParentId(), bomTree.getBomType());
                 
                 if (Long.valueOf(0L).equals(bomTree.getParentId())){
-                    treeId = bomTree.getId();
                     log.info("[COST_CALC] This is ROOT node (ParentId=0)");
                 }
                 
@@ -433,11 +447,13 @@ public class QuoteDetailServiceImpl extends ServiceImpl<QuoteDetailMapper, Quote
                 log.info("[COST_CALC] Accumulating to total - After: LabourCost={}, MachineCost={}", labourCost, machineCost);
             }
             // 计算最终成本
-            List<QuoteDetailBom> boms = bomMap.get(treeId);
-            if (Objects.nonNull(boms)){
-                for (QuoteDetailBom bom : boms) {
-                    unitQuotePrice = unitQuotePrice.add(bom.getQuoteUnitPrice());
-                    actualQuotePrice = actualQuotePrice.add(bom.getActualQuotePrice());
+            if (Objects.nonNull(rootTreeId)) {
+                List<QuoteDetailBom> boms = bomMap.get(rootTreeId);
+                if (Objects.nonNull(boms)) {
+                    for (QuoteDetailBom bom : boms) {
+                        unitQuotePrice = unitQuotePrice.add(bom.getQuoteUnitPrice());
+                        actualQuotePrice = actualQuotePrice.add(bom.getActualQuotePrice());
+                    }
                 }
             }
             log.info("[COST_CALC] [PERF_LOG] Main convolution loop took {} ms, out of which DB updates took {} ms", (System.currentTimeMillis() - perfConvolutionStartTime), totalUpdateDbTime);