Hybridoma technology was used to prepare 3α-HSD monoclonal antibody. Using 3α-HSD to express and purify as antigen to immune Balb/c mice,the sensitization of B lymphocytes that against the antigen was gained. The hybridoma cell lines is got by fusing the B lymphocyte cell with SP2/0. Screen positive hole in ELISA,then the cell lines is cloned and the last is to screen the cell lines stabling to secrete 3α-HSD monoclonal antibody hybridoma. Although cell lines which could secrete monoclonal antibody hybridoma against 3α-HSD have been gotten,many special phenomenons were discovered during the preparation,such as qing on hybridoma with single ascites titer resistance is too low,but high serum titer. In the process of preparing single resistance,a preliminary analysis for against3α-HSD monoclonal antibody preparation were made and technical support would be provided.