Abstract: Objective To investigate the effects of intraperitoneal hyperthermic perfusion chemotherapy on immune function, tumor markers, perioperative complications and side effects in patients with colorectal cancer after operation. Methods Clinical data about 256 cases with colorectal cancer who received anterior resection from January 1, 2016 to December 31, 2017 were retrospectively analyzed. Of the 256 cases, 112 patients who received intraperitoneal hyperthermic perfusion chemotherapy combined with intravenous chemotherapy after operation were defined as the combinative treatment group and 144 patients who received intravenous chemotherapy alone as the chemotherapy group. The levels of inf l ammatory factors, T lymphocyte ratio, tumor markers, perioperative complications and side effects were compared between the two groups. Results The baseline data were well matched in two groups (all P＜ 0.05). At 1 day after surgery, TNF-α, CRP, IL-6 in the combinative treatment group were significantly lower than those in the chemotherapy group TNF, (62.86±9.13) ng/L vs (66.42±11.72) ng/L; CRP, (46.47±7.58) ng/L vs (49.31±10.03) ng/L; IL-6, (40.27±8.36) ng/L vs (43.29±9.66) ng/L; all P＜ 0.05. The percentages of CD3⁺, CD4⁺ T lymphocyte and ratio of CD4⁺ to CD8⁺ in the combinative treatment group were higher than those in the chemotherapy group after 4 cycles of chemotherapyCD3⁺, (71.83%±8.61%) vs (68.77%±9.18%); CD4⁺, (31.64%±4.83%) vs (30.01%±5.06%); CD3⁺/CD4⁺, (1.17%±0.15%) vs(1.10%±0.19%), all P＜ 0.05. There was no significant difference in complications (anastomotic leakage, incision infection, intra-abdominal hemorrhage, intestinal obstruction), the incidence of myelosuppression, vomiting, diarrhea, oral mucositis after chemotherapy and distant metastasis and survival between the two groups (all P＞ 0.05). Local recurrence in combinative treatment group was lower than that in chemotherapy group (0 vs 5.6%, P＜ 0.05). Conclusion Compared with intravenous chemotherapy alone, intraperitoneal hyperthermic perfusion chemotherapy combined with intravenous chemotherapy can reduce the release of inf l ammatory factors, improve the immune function of patients with colorectal cancer, reduce local recurrence of tumor, and it does not increase perioperative complications and adverse reactions during chemotherapy.