Objective: To study the relationship between the expression of human cyclin B1 in colorectal carcinomas and the pathological characters. Methods: The Expression of cyclin B1 in 66 cases of colorectal carcinomas were detected by flow cytometry and immunohistochemistry. Then the relationship between the expression of cyclin B1 in colorectal carcinomas and pathological characters was analyzed with statistics. Results: The expression of cyclin B1 in colorectal carcinomas had associa- tivity with the cancer cell differentiation (P<0.05); However, the expression of cyclin B1 in colorectal carcinomas had no obvious associativity with cancer cell infiltrate depth and lymph nodes metastasis (P>0.05). Conclusion: In the colorectal cancers with high expression of cyclin B1, the cancer cells would present high differentiation; with low expression of cyclin B1 the cancer cells would present low differentiation. Along with the expression of cyclin B1 from high to low, the cancer cells differentiation has the tendency from high to low too. Objective: To study the relationship between the expression of human cyclin B1 in colorectal carcinomas and the pathological characters. Methods: The Expression of cyclin B1 in 66 cases of colorectal carcinomas were detected by flow cytometry and immunohistochemistry. Then the relationship between the expression of cyclin Results: The expression of cyclin B1 in colorectal carcinomas had associativity with the cancer cell differentiation (P<0.05); However, the expression of cyclin B1 in colorectal carcinomas had no obvious The associativity with cancer cell infiltrate depth and lymph nodes metastasis (P>0.05). . Along with the expression of cyclin B1 from high to low, the cancer cells differentiatio n has the tendency from high to low too.