〔Abstract〕 Objective To investigate the correlation between deceleration capacity of rate(DC)and heart rate variability(HRV) in patients with colorectal cancer. Methods A total of 143 patients diagnosed with colorectal cancer in the Department of Colorectal Oncology of the First Affiliated Hospital of Xiamen University from January 2019 to December 2019 were selected. Ambulatory electrocardiography were performed before surgery, chemotherapy and radiotherapy and deceleration capacity of rate and heart rate variability were analyzed in patients. Result The results showed that SDNN, SDANN index and DC were significantly lower in stage III and IV colorectal cancer patients than those in stage 0, I and II, and there were positive correlation between DC and SDNN, SDANN index, RMSSD, trigonometric index, VLF, LF and HF. Conclusion The patients with colorectal cancer undergoing ambulatory electrocardiography examination can be a sensitive indicator in early diagnosis of autonomic system damage and judge the course of the canner, so as to give intervention treatment in time and improve the prognosis of patients.