Objective To detect the active infection of HCMV .The early infection marker pp65 was expressed and used for preparing antibody.Methods The expression vectors containing whole pp65 gene and one hydrophilic and antigenic domain of pp65(pp65 hp) were constructed and induced to express in E.coli, respectively. Western Bolt was applied to test the antigenicity of recombinant protein.ResultWhole pp65 was expressed at low level, less than 5% of total bacteria protein; while high efficient expression was observed for rp65 hp, approaching 40% of total protein in bacteria. Western Bolt result showed that rp65hp reacted with HCMV IgG antibody.Conclusion Recombinant rp65hp was antigenic and can be used to prepare antibody for detection of early HCMV infection.