Abstract: Using the human cervical cancer, oncoprotein P21 is detected and analysied by 4 index in the same one speciman. The results showed that there is p21 expression in cervical cancer and Mw is 21Kd in p21. Main part of p21 expression is in the cell plasma and the membrane of carcinoma cell. Level of expression is 6 time more than that of cervilis. These resultes have be verified in clinical application. 54 section have teteced with ABC immunohistochemstry. p21 positive rate and strength of cervical cancer are strikingly bighter those of cervitis. (P0.05) The data imply that p21 Mcab may be a marker on diagnosis of cervical cancer and p21 McAb may paly an impo rtant role on diagnose and other clinical application.