Objective: The aim of this study was to investigate the effect of factors such as neutrophils lymphocytes ratio(NLR) on the prognosis of patients with treated metastatic colorectal cancer who undergo immunotherapy, and the associated factors that influence the efficacy of immunotherapy. Methods: Colorectal cancer patients who attended the Department of Oncology of the Second Affiliated Hospital of Air Force Medical University from October 2019 to February 2023 were initially enrolled in this study, and 127 patients were finally included after the inclusion and exclusion criteria. Statistical methods were used to analyze the effects of whether or not to receive immune checkpoint inhibitors, the type of immune checkpoint inhibitors, and NLR on the evaluation of the efficacy of tumor treatment for patients with treated metastatic colorectal cancer. The effects of different factors such as gender, tumor site, KRAS status, mismatch repair protein(MMR), and NLR on the prognosis of treated metastatic colorectal cancer. Results: Of the 127 patients, 65 received immunotherapy and 62 did not. There was no statistically significant difference between the therapeutic efficacy of domestic and imported immune checkpoint inhibitors for metastatic colorectal cancer patients who had previously received more than one first-line treatment . Kaplan-Meier survival curves plotted by SPSS found that there was a statistical difference between NLR ( P=0.007) and MMR (P=0.029) for progression free survival(PFS) in patients with treated metastatic colorectal cancer.Cox univariate survival analysis found that NLR (P=0.012) and MMR (P=0.046) were two factors affecting PFS in colorectal cancer patients. Cox multivariate analysis concluded that NLR<3 (P=0.024) was an independent risk factor affecting survival time of patients with treated metastatic colorectal cancer who received immune checkpoint inhibitors, with a statistically significant difference. Conclusion: For patients with treated metastatic colorectal cancer, NLR and MMR are important indicators of PFS, and NLR<3 is an independent risk factor for survival time of patients with treated metastatic colorectal cancer who receive immune checkpoint inhibitors, which has an important predictive value of prognosis.