Expression vector carrying cyclooxygenase-2（COX-2） gene was constructed by inserting the C-terminal 777 bp fraction amplified by PCR into the vector pET-28b（+）.The fusion protein was expressed in the form of inclusion body after induction by IPTG in BL21（DE3）.Using Ni-NTA chelating column

the fusion protein was highly purified.The polyantibody was prepared by immunizing the rabbits with five injections of the purified protein.ELISA and Western Blotting were performed to test its specificity and sensitivity.Meanwhile

cyclooxygeanse-2 expression was detected in hepatocellular carcinoma and surrounding noncancerous liver tissues by Western Blotting using the antiserum.The polyantibody can recognize cyclooxygease-2 with high specificity and sensitivity and cyclooxygenase-2 was expressed at higher level in hepatocellular carcinoma compared to that in surrounding noncancerous liver tissues.Preparation of cyclooxygeanse-2 polyantibody make it possible to further study the biological functions.