Objective To explore the clinical value of carbon nanocomposite suspension injection in TNM staging of colorectal cancer.Methods A prospective,randomized,controlled clinical trial was conducted in July 2021 in the Department of Colorectal Surgery,Nanjing Drum Tower Hospital.After the patients were qualified,they were randomly assigned to study group and control group,and 200 evaluable cases were planned to be included in each group.The patients in the study group underwent colonoscopy and were injected with carbon nanocomposite suspension.The patients in the control group were treated with routine operation,and no carbon nano-suspension was injected before operation.The number of lymph nodes detected,the number of positive lymph nodes detected and the lymph stages were compared between the two groups.Results A total of 361 patients were enrolled in the clinical study,including 179 patients in the study group and 182 patients in the control group.The total number of lymph nodes obtained in the study group was 20.2±5.9,which was significantly higher than that in the control group(15.0±5.5)(t=8.584,P<0.001).The total number of positive lymph nodes in the study group was 1.6±3.9,which was significantly higher than that in the control group(0.8±1.9)(t=2.852,P=0.005).In the study group,97 patients(54.2%)were N0,56 patients(31.3%)were N1,and 26 patients(14.5%)were N2.In the control group,115 patients(63.2%)were N0,57 patients(31.3%)were N1,and 10 patients(5.5%)were N2.There was significant difference in lymph staging between the two groups(x2=8.624,P=0.013).Conclusion The application of nano-carbon in lymph node tracing navigation for colorectal cancer can obtain more lymph nodes and positive lymph nodes,and thus obtain more accurate and objective lymph node staging,judge prognosis and guide follow-up treatment plan.