Abstract: Objective: The active free oxygen radicals broken out by respirationc of human polymorphoneuclear neutrophil are the biochemical basis of defence mechanism in human body. Our study was aimed to determine the levels of peak value of leukocyte chemiluminescence （LC） so that to reflect the ability of disinfection of white blood cells. Methods: The pictures of LC were studied from the patients with GI cancer supported by TPN with or without fat emulsion perioperatively. 14 of such cases comfired diagnosis of advanced gastric or colonic cancers were divided into two groups: （1）TPN with fat emulsion group. 30% nonprotein calories （NPC） was provided by 20% Lipovenoes. （2）TPN with glucose group. 100% NPC was provided by glucose. Overall other nutrients, nitrogen and carolies were given same in both groups. Results: The results showed that the pictures of LC were not significant difference pre and postoperatively, but the LC was more brightened after 4 days than that of preoperation in group Ⅰ （P＜0.01）;but was not significantly different in group Ⅱ （P ＞0.05）. Conclusion: （1）The operation trauma of GI cancer does not affect the LC. （2）TPN with 30% NPC provided by 20% Lipovenoes may brighten the LC in patients with GI cancer postoperatively.