In order to study the effects of phosphodiesterase during the differentiation of venom gland cells by means of immunohistochemical techniques,the antigen with the phosphodiesterase activity from the venom of the snake Agkistrodon blomhoffii brevicaudus was prepared. The antigen was purified from the venom through ion-exchange chromatograph by using DEAE-Sephadex A-50,gel filtration on Sephadex G-100. The antigen shows the activity of phosphodiesterase(as measured with bis-4-nitrophenylphosphate as substrate). The homogeneity of the antigen was exhibited by polyacrylamide gel electrophoretic criterion. Its molecular weight is 20900 Dalton,as determined in SDS polyacrylamide gel electrophoresis. It might be helpful in developing monoclonal antibody.