Abstract: Objective: To explore expression of the SUZ12 of PRC2 subunit in colorectal cancer tissue,and its correlation with clinical pathological features.Methods: Eighty-five patients treated with laparoscopic colorectal cancer resection were investigated,the colorectal cancer specimen during surgical resection was collected,and all patients were not treated with chemoradiation therapy before operation.The normal tissue distance from carcinoma tissue edge for 15 cm was set as the control group.The protein content of SUZ12 in colorectal cancer tissue and normal tissue were determined.The expression level of SUZ12 in colorectal cancer tissue was evaluated according to the proportions of positive staining intensity and positive cell nucleus.Results: The positive marking scores of comb SUZ12 protein in left half colon cancer group,transverse colon cancer group,right half colon,sigmoid colon cancer,rectal cancer group and control group increased(P<0.05 to P<0.01).The positive marker scores of SUZ12 in TNM stage Ⅲ to Ⅳ colorectal cancer were higher than that in TNM stage Ⅰ to Ⅱ colorectal cancer(P<0.01),the positive marker scores of SUZ12 in moderate and high differentiation carcinoma tissue were higher than those in undifferentiated and low differentiation carcinoma tissue(P<0.01),and the positive marker score of SUZ12 in colorectal cancer with lymph node metastasis was higher than that in colorectal cancer without lymph node metastasis(P<0.01).The differences of the positive marker scores of SUZ12 in age and sex of patients,tumor diameter,tumor site and tumor infiltration depth were not statistically significant(P>0.05).Conclusions: SUZ12 protein can be used as the evaluation index of tumor malignant degree,which is crucial in the early diagnosis of colorectal cancer,improving treatment and prolonging the survival time of patients.