Objective To determine whether neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) are important prognostic factors in patients with colorectal cancer, and to clarify relationship between NLR or PLR and TNM staging in colorectal cancer. Methods The clinical data of 304 patients with colorectal cancer who were admitted to the same medical group from January 2013 to December 2013 in the West China Hospital of Sichuan University were analyzed retrospectively. The relationship between NLR or PLR and the clinicopathologic characteristics and its effects on prognosis of patients with colorectal cancer were analyzed. Results The critical values of NLR (sensitivity=51.0%, specificity=75.4%, area under the receiver operating characteristic curve=0.66) and PLR (sensitivity=73.0%, specificity=46.4%, area under the receiver operating characteristic curve=0.60) was 2.27 and 155.92, respectively, with a 3-year cumulative survival rate as the end point. According to the critical values of NLR and PLR, there were 133 cases in a low NLR group (NLR≤2.27), 171 cases in a high NLR group (NLR>2.27), 207 cases in a low PLR group (PLR≤155.92), 97 cases in a high PLR group (PLR>155.92). ① The 3-year survival rate was 91.5% and 77.2% in the low NLR group and the high NLR group, respectively, which was 89.0% and 72.8% in the low PLR group and the high PLR group, respectively. The survival curves of NLR and PLR on prognosis prediction had significant differences (P=0.002, P=0.001). ② The results of multivariate analysis showed that the NLR was the independent risk factor for colorectal cancer (P=0.004), whereas PLR was not the independent risk factor for colorectal cancer (P=0.408). ③ The NLR and PLR were associated with the tumor TNM staging (P=0.002, P=0.000), which in the colorectal cancer with stage Ⅳ was significantly higher than those with stage Ⅰ–Ⅲ (P<0.05). ④ The NLR and PLR were associated with T stage (P=0.006, P=0.031). The NLR in the colorectal cancer with stage T4 was significantly higher than that with stage Ⅰ (P=0.015) or stage Ⅱ (P=0.032). The PLR in the colorectal cancer with stage T4 was significantly higher than that with stage Ⅱ (P=0.013). ⑤ The NLR was not associated with N staging (P=0.118). The PLR was associated with N staging (P=0.007), which in the colorectal cancer with N2 stage was significantly higher than that with N0 stage (P=0.008) or N1 stage (P=0.019). ⑥ The NLR and PLR in the colorectal cancer with stage M1/M2 were significantly higher than those with stage M0 (P=0.004, P=0.001). Conclusions Preliminary results of this study show that NLR is an important independent prognostic indicator for patient with colorectal cancer. While PLR is significantly increased when lymph node metastasis occurs, and platelet elevation might be related to lymph node metastasis.