Abstract: Objective：To explore T-lymphocyte subgroups immune function of advanced colorectal cancer patients and its clinical significance. Methods：The change of T-lymphocyte subgroups was measured with flow cytometry before and after treatment in the patients with advanced colorectal cancer compared with the healthy control group. Results：The 84 cases of advanced colorectal cancer in patients with T-lymphocyte subgroups compared with 35 cases of normal control group, CD4⁺,CD8⁺CD28⁺,CD28⁺ were significantly lower than the control group (P<0.01), CD8⁺CD28^- was higher than control group (P<0.01),CD3⁺,CD8⁺,CD4⁺/CD8⁺ ratio were no significant difference compared with the control group(P>0.05).The 69 cases were respected chemotherapy,clinical benefit of 39 cases,after chemotherapy,CD3+ were higher than that in pre-treatment (P<0.05), CD8⁺,CD8⁺CD28^- were significantly lower (P<0.01), CD4⁺,CD8⁺CD28⁺、CD28⁺,CD4⁺/CD8⁺ ratio were significantly higher (P<0.01); clinical ineffective of 30 cases, after chemotherapy, CD8⁺、CD8⁺CD28^- were significantly higher than that in pre-treatment (P<0.01), CD4⁺、CD4⁺/CD8⁺ ratio were significantly lower (P<0.01), CD28⁺ were lower (P<0.05), CD3⁺、CD8⁺ CD28⁺were lower,but no significant difference (P>0.05). Conclusion ：The immunity was suppressed in the patients with advanced colorectal cancer and immunity of the patients can be improved by effective chemotherapy.So clinical observation to the T-lymphocyte subgroups expression,in particular the joint detection CD8⁺CD28⁺、CD8⁺CD28^-、CD28⁺Tcells to assess advanced colorectal cancer cells in patients with immune function and disease is more positive clinical significance.