Abstract: Objective To investigate the levels of carcinoembryonic antigen（CEA）， carbohydrate antigen（CA）125 and CA19-9 in postoperative peritoneal fluid drainage of colorectal cancer（CRC） and their relationship with clinical staging and peritoneal micrometastasis. Methods The peritoneal fluid drainage on postoperative day 1 was collected from 86 patients with CRC（CRC group） and 30 patients with benign intestinal disease（control group）.The levels of CEA， CA125 and CA19-9 in postoperative peritoneal fluid drainage of CRC were detected and their relationship with clinicopathological features were analyzed. Results The level of CEA was higher in CRC group than that in the control group（P＜0.05）， while there was no significant difference in CA125, CA199 between both groups（P＞0.05）. There was significant correlation between the state of lymph node metastasis， depth of invasion and clinical stage with the level of CEA， while no relationship was found between the levels of CA125, CA199 and clinicopathological features. Conclusion The level of CEA in postoperative peritoneal fluid drainage of CRC can be used to predict clinical staging， peritoneal micrometastasis and prognosis.