The transmembrane protein (TM) encoded by gp37 gene plays a critical role when virus fusion with cell membrane occurs. Several highly conserved regions in TM are important targets for antivirus studies. Studies on structure and function of TM will provide basic information for anti-retrovirus, especially for avian leukosis virus. In the study, gp37 gene was amplified by PCR from the Chinese strain ALV-J-WS0701. The gp37 gene was cloned into pMD18-T vector, and was sequenced. Then, pFast-BacHTb-gp37 vector was constructed and expressed by baculovirus expression vector system. The expression product of gp37 gene was analyzed by indirect immunofluorescence assay and Western blot. The results showed that positive green fluorescence was present in sf9 cells infected with recombinant virus and a protein band with a molecular weight of 21kD was present in Western blot. It is concluded that gp37 gene was expressed in sf9 cells infected with recombinant virus successfully.