Objective To study the association between preoperative peripheral blood neutrophil-to-lymphocyte ratio (NLR) and pathological states in colon cancer. Methods We collect the clinical data of 77 patients and make a contrast between the NLR of the patients with colon cancer and healthy individuals. The relationship of NLR between different pathological states and other tumor markers is calculated. Results The preoperative NLR of patients with colon cancer (3.13,1.88-3.89) is significantly (P=0.000) higher than that of healthy individuals (1.43,1.18-1.85). Preoperative NLR is related to tumor differentiation (P<0.05). Compared with the NLR of moderate and high differentiated colon cancer, the NLR of low-differentiated colon cancer is the highest. There is no significant difference in preoperative NLR between CEA and CA19-9 positive and negative groups. Conclusion Preoperative peripheral NLR is related to the degree of differentiation of colon cancer. Patients with low-differentiated colon cancer have a higher preoperative NLR. Preoperative NLR plays an important role in diagnosis and prognosis of colon cancer.