OBJECTIVE To explore the diagnosis and treatment of the aneurysm in the common trunk of malformed superior mesenteric artery and celiac trunk, especially the approach how to expose and excise such aneurysm. METHODS The clinical data of 6 patients with aneurysm in the common trunk of malformed superior mesenteric artery and celiac trunk, who were operated on under general anesthesia from 1998 to 2006, were analyzed. At first, the body of pancreas was isolated and retracted, the malformed celiac trunk and its ramification were blocked and ablated, the initial part of the celiac trunk and the distant end of left gastric artery were ligated, and then by-pass operation was operated from infra-renal aorta to the visceral arteries (hepatic, splenic, and superior mesenteric arteries) with artificial blood vessels. Follow-up was conducted for 1 - 8 years. RESULTS Five cases underwent aneurysm ablation and by-pass from aorta to hepatic, splenic, and superior mesenteric arteries; while 1 case underwent aneurysm ablation and spleen ablation, superior mesenteric artery reconstruction, and by-pass from aorta to hepatic artery simultaneously. All patients were cured without complication and recurrence. No arterial anastomosis stricture or stenosis was found in the 5 patients who received by-pass from aorta to hepatic, splenic, or superior mesenteric artery; however, slight stricture was found at the repaired portion of superior mesenteric artery in another one patient, but without any arterial anastomosis stricture in aorta or hepatic artery. CONCLUSIONS It is an effective and safe method to treat the aneurysm common trunk of malformed superior mesenteric artery and celiac trunk by using the artificial blood vessel by-pass from aorta to visceral arteries (hepatic, splenic, and superior mesenteric arteries) after controlling the initial part of common trunk and cutting off the aneurysm there.