Objective of the present study was to investigate the effects of peripherally inserted central catheter (PICC) parenteral nutrition support on immune function and nutritional support in patients undergoing radical gastrectomy for gastric cancer. 140 patients who underwent radical gastrectomy for gastric cancer were selected as participants and were divided into study group and the control group by random number table, with 70 cases in each group. Patients in the two groups underwent standard gastrectomy under general anesthesia by the same group of doctors. The study group received postoperative PICC catheter parenteral nutrition, and the control group received central venous catheter (CVC) nutrition support. Comparative study was done using t test and Chi-square test. The serum levels of ALB, TFN, PA, Hb, CD4+, CD8+, CD4+/CD8+, IgA, IgG, IgM and CD3+ in the two groups were observed before and after treatment, and the postoperative complications of the two groups were compared. After treatment, the levels of ALB, TFN, PA and Hb in the two groups were significantly increased (P<0.05). Levels of CD3+, CD4+, CD4+/CD8+, IgA, IgG and IgM also amplified significantly after treatment in both the groups, while CD8+ decreased significantly (P<0.05). What's more, the improvement degree of the study group was significantly greater than that of the control group (P<0.05). The time of drawing drainage tube, recovering intestinal function, getting off bed and the length of hospital stay in the study group were significantly shorter than those in the control group (P<0.05). The incidence of postoperative complications in the study group and control group were 8.6% (6/70 cases) and 11.4% (8/70 cases) respectively, and there was no significant difference (P>0.05). PICC catheter parenteral nutrition support and improve the nutritional status of patients, it was proved a safe and effective nutritional support which improve the cellular immune function and accelerated the recovery of gastrointestinal function.