Abstract: Excellent mechanical properties of 27SiMn hydraulic support can be achieved by heat treatment. In this paper heat treatment orthogonal experiments with four factors and three levels were performed to investigate the effects of quenching temperature and holding time as well as tempering temperature and holding time on the mechanical properties of the hydraulic support. The heat treatment process was optimized as quenching after holding at 930℃ for 40 min and then tempering at 480℃ for 50 min. At these optimized heat treatment parameters, the hydraulic support has excellent comprehensive mechanical properties:the yielding strength of 895 MPa, the tensile strength of 1 030 MPa, the elongation of 15%, the area reduction of 54%, and the impact energy of 53. 3 J, which meet the requirements of 27SiMn steel according to the standard GB/T 17396-1998.