The D2 plus complete mesogastrectomy, based on the membrane anatomy theory, significantly enhances the thoroughness and safety of lymph node dissection by utilizing the natural embryonic developmental planes. In the No.11p lymph node area, dissection along the avascular plane between the Treitz fascia and the splenic arterial vascular sheath enables en bloc resection of lymph node adipose tissue, preventing residual micrometastases. For No.12 lymph node dissection, precise separation of the extra-Glissonian plane ensures complete skeletonization of the proper hepatic artery, reducing the risk of tumor cell shedding. The concept of membrane anatomy emphasizes operating anterior to the splenic arterial sheath to avoid the area posterior to the pancreas where the splenic vein courses. During No.12 lymph node dissection, protection of the portal vein and common bile duct relies on identifying the layers within the hepatoduodenal ligament to prevent excessive deep dissection. During No.11p lymph node dissection, adhering closely to the splenic arterial sheath prevents incision into the pancreatic parenchyma, thereby reducing the risk of pancreatic fistula. Thorough dissection of No.11p and No.12 lymph nodes is crucial for preventing local recurrence. The “complete mesogastric excision” principle of membrane anatomy minimizes intraperitoneal tumor cell dissemination, creating favorable conditions for subsequent adjuvant therapy.