Balb/c mice were immunized four times by the purified fusion CA protein which was emulsified with freund′s adjuvant. Then, cell fusion was conducted according to standard procedure. Positive hybridoma clones were screened by indirect ELISA and Western blot. Three hybridoma clones that stably secreted specific monoclonal antibody against JSRV-CA were developed. Meanwhile, JSRV ca gene was divided into four overlapping fragments and expressed in E. coli BL21 respectively. Pepscan technology was employed to screen the antigen epitope through the expressed fusion proteins were detected respectively with three McAbs by Western blot. Then three liner epitopes recognized by three McAbs were preliminary identified, and the functional affinities of anti-CA McAbs were assessed with non-competitive ELISA method. All this may be helpful in understanding molecular properties of JSRV-CA and may be useful for pathogenic diagnosis and vaccine design.