Abstract: 【Abstract】 Object To investigate the expressions of cyclinD1 CDK4 in pancreatic cancer and their relationships with clinlicopathological parameters. Methods Immunohistochemical detector with new second generational tow steps method was used to detect the expressions of cyclinD1 CDK4 and PCNA in 48 cases of pancreatic cancer and 14 cases of chronic pancreatitis. Results The expressions of cyclinD1 CDK4 proteins in pancreatic cancer were 70.85%（34/48）and 62.50%（30/48） respectively .The cyclinD1 and CDK4 proteins were increased（P<0.01）, as compared with that in chronic pancreatitis. The positive rates of cyclinD1 and CDK4 in the pancreatic cancer of well-differentiation, without metastasis and clinical stage Ⅰ/Ⅱwas significantly lower than that in the cases of poor differentiation ,with metastasis and clinical stage Ⅲ/Ⅳ（P<0.05）.The PCNA counting score in cyclinD1 positive group was higher than those in cyclinD1 negative group（P<0.01）; The PCNA counting score in cyclinD1 positive group was higher than those in cyclinD1 negative group（P<0.05）.Concluslons: cyclinD1 and CDK4 are attend to the carcinogenesis and progression of pancreatic cancer, and is related to the activity of cell proliferation . Examination of CyclinD1 and CDK4 may be as an marker to judge biological behavior of pancreatic cancer.