Objective To explore the effect of different nutrition on the immune function of patients with colorectal cancer. Methods A total of 640 colorectal cancer patients were randomized into the enteral nutrition and peripheral nutrition groups. The peripheral venous blood was sampled before operation and on the postoperative days 1 and 7 to determine the serum levels of IgG, IgA, IgM, the percentage of T lymph cell subgroups CD3, CD4, CD4/CD8 and CRP, PGE, α- antitrypsin etc. The patient’s general condition, side-effects, and complications were observed intimately after surgery. Results Compared with the control group, the IgG, IgA, IgM, CD3, CD4,CD4/CD8 levels of the trial group on postoperative day 7 were higher. But the levels of CRP, PGE, α- antitrypsin were decreased. Hospitalization time and anal exsufflation time were shorter as well. There was no significant difference in either the general conditions or complications between the two groups. Conclusion Application of enteral nutrition after colorectal cancer surgery is safe, ,effective, and can improve the patient’s immune function and prognosis.