Abstract: According to the characteristics of steel with yield strength of 900 MPa used in advanced hydraulic support, the microstructure and hardness of heat affected zone (HAZ), hydrogen assistant cracking susceptibility and influence of welding parameters on microstructure and mechanical properties of welded joint were investigated. The results show that the HAZ of SHT900D steel has stronger hard quenching tendency, proper measures must be taken to prevent hydrogen assistant cracking.Welding parametens have a certain influence on the microstructure and mechanical properties of welded joint, and heat input and interpass temperature should be controlled properly to obtain a desired welded joint.The welding procedure determined by this test had been used in welding production of advanced hydraulic support successfully.