Abstract: Objective To investigate the risk factors of colorectal cancer and prov ide scientific basis for monitoring and preventing this disease.Methods A1B2 matched case-control study was carried out in Shandong including 1 869 cases with colorectal cancer and 3 738 controls.Data were analyzed with conditional Logistic regression.Results The independent r isk factors for colorectal cancer were the frequencies of intake of meat,frying food in oil,frying meat treated with high temperature,history of bowel polyps,history of fecal mucohemor rhage,psychic attack and relatives who suffered from colorectal cancer.The OR value were respectively 2.375,2.383,2.706,11.024,5.365,2.553 and 2.527;Favor of eating garlic,diet ary fibers and 1ight physical activities were protective factors.The corresponding OR were 0.532,0.784 and 0.739;There was obviously no correlative between incidence of colorectal cancer and following factors:smo king,drinking,tea,fruits and milk products.Conclusion The occurr ence of colo rectal cancer in Shandong was related to dietary,the poor ability for adjusting mood,the history of intestinal diseases and family history of tumors.Favor of eating garlic was probably protective factors.