Objective To investigate the safe distance of upper gastric cancer by pokemon protein. Methods In 60 cases of upper gastric cancer， specimens were get from tumors’ tissue and every 0.5 cm from the proximal of tumor margin beginning at the 1.0 cm to distal. Western blot method was used to test the expression of pokemon protein. Results There were 38 cases （63.3%） positively expressed pokemon protein. Compared with the center of tumor， the positive expression rates of pokemon protein at every sites of 2.5-5.0 cm from margin were lower （P＜0.003）， but didn’t signi-ficantly differed at every sites of 1.0-2.0 cm from margin （P≥0.003）. When the incisal margin distance of more than 3.5 cm of both sides， the positive expression rate of pokemon protein were 0. There were no significant difference between the corresponding sites of the upper resection margin and lower resection margin （P＞0.05）. Conclusions The results show that 3.5 cm may be the molecular margin basing on the positive expression of pokemon protein in the surgical margin of upper gastric cancer， which may have guiding significance to the surgical margin.