diff --git a/erpnext/manufacturing/doctype/production_plan/production_plan.py b/erpnext/manufacturing/doctype/production_plan/production_plan.py
index 8a35d2aced..4290ca3e4c 100644
--- a/erpnext/manufacturing/doctype/production_plan/production_plan.py
+++ b/erpnext/manufacturing/doctype/production_plan/production_plan.py
@@ -559,9 +559,11 @@ class ProductionPlan(Document):
 			get_sub_assembly_items(row.bom_no, bom_data, row.planned_qty)
 			self.set_sub_assembly_items_based_on_level(row, bom_data, manufacturing_type)
 
-	def set_sub_assembly_items_based_on_level(self, row, bom_data, manufacturing_type=None):
-		bom_data = sorted(bom_data, key = lambda i: i.bom_level, reverse=True)
+		self.sub_assembly_items.sort(key= lambda d: d.bom_level, reverse=True)
+		for idx, row in enumerate(self.sub_assembly_items, start=1):
+			row.idx = idx
 
+	def set_sub_assembly_items_based_on_level(self, row, bom_data, manufacturing_type=None):
 		for data in bom_data:
 			data.qty = data.stock_qty
 			data.production_plan_item = row.name
diff --git a/erpnext/manufacturing/doctype/production_plan/test_production_plan.py b/erpnext/manufacturing/doctype/production_plan/test_production_plan.py
index 2febc1e23c..21a126b2a7 100644
--- a/erpnext/manufacturing/doctype/production_plan/test_production_plan.py
+++ b/erpnext/manufacturing/doctype/production_plan/test_production_plan.py
@@ -347,6 +347,45 @@ class TestProductionPlan(ERPNextTestCase):
 
 		frappe.db.rollback()
 
+	def test_subassmebly_sorting(self):
+		""" Test subassembly sorting in case of multiple items with nested BOMs"""
+		from erpnext.manufacturing.doctype.bom.test_bom import create_nested_bom
+
+		prefix = "_TestLevel_"
+		boms = {
+			"Assembly": {
+				"SubAssembly1": {"ChildPart1": {}, "ChildPart2": {},},
+				"SubAssembly2": {"ChildPart3": {}},
+				"SubAssembly3": {"SubSubAssy1": {"ChildPart4": {}}},
+				"ChildPart5": {},
+				"ChildPart6": {},
+				"SubAssembly4": {"SubSubAssy2": {"ChildPart7": {}}},
+			},
+			"MegaDeepAssy": {
+				"SecretSubassy": {"SecretPart": {"VerySecret" : { "SuperSecret": {"Classified": {}}}},},
+																# ^ assert that this is
+																# first item in subassy table
+			}
+		}
+		create_nested_bom(boms, prefix=prefix)
+
+		items = [prefix + item_code for item_code in boms.keys()]
+		plan = create_production_plan(item_code=items[0], do_not_save=True)
+		plan.append("po_items", {
+			'use_multi_level_bom': 1,
+			'item_code': items[1],
+			'bom_no': frappe.db.get_value('Item', items[1], 'default_bom'),
+			'planned_qty': 1,
+			'planned_start_date': now_datetime()
+		})
+		plan.get_sub_assembly_items()
+
+		bom_level_order = [d.bom_level for d in plan.sub_assembly_items]
+		self.assertEqual(bom_level_order, sorted(bom_level_order, reverse=True))
+		# lowest most level of subassembly should be first
+		self.assertIn("SuperSecret", plan.sub_assembly_items[0].production_item)
+
+
 def create_production_plan(**args):
 	args = frappe._dict(args)