Abstract: The vacuum diffusion welding method was used to join 6063 aluminum alloy micro-channel cooling plates. The interfacial morphology and interfacial bonding force of 6063 aluminum alloy diffusion welded joints were studied,and effects of different press amount（ 0. 2 mm,0. 5 mm,0. 7 mm） on microstructure and mechanical properties of diffusion welded joints were researched. Meanwhile,diffusion welded joints were treated by gas quenching and differences of microstructure and properties of diffusion welded joints between before and after gas quenching were compared and analyzed. The results showed that the side wall of the channel presented upsetting phenomenon after diffusion welding,and the bigger pressure amount was,the more obvious upsetting phenomenon was. When diffusion bonding temperature was 520 ～ 540 ℃,holding time was 90 min and press amount was 0. 5 mm,the diffusion bonding interface could achieve uniform,continuous and compact microstructure.Average tensile strength of the joint reached 84. 5 MPa,which was more than 90% of that of base metal after welding. After gas quenching treatment of diffusion welded joints,a large number of fine dispersed Mg2 Si dispersion strengthening phases were observed in the matrix. Rockwell hardness of the joint increased from 78. 2 HRL to 98. 6 HRL and tensile strength of the joint reached 186. 5 MPa.