The envelope glycoprotein D gene of pseudorabies virus Ea strain was cloned by PCR technique. Sequence analysis displayed 98% nucleotide sequence homology and 97% deduced amino acid sequence homology between the cloned gD gene and PRV Rice strain gD gene. Then gD gene was expressed highly in the baculovirus GST fusion vector system. Both SDS-PAGE and Western-blot verified that the expression product was GST-gD fusion protein with the molecular mass of 71 ku. Expressed GST-gD fusion protein accounted for about 20% of total cellular protein. The protective immune assay was performed in mice by using GST-gD fusion protein as antigen. The result showed that all mice immunized by GST-gD could produce a certain level of antibody against PRV gD(antibody titer: 1∶128), and the mice in immunized group could be partly protected against challenge infection of highly virulent PRV Su strain at 2×10⁵ PFU per mice. A good foundation has been laid down for developing PRV genetically-engineered subunit vaccine.