Abstract: A nondestructive testing method based on magnetic properties of materials was explored to comprehensively evaluate the heat treatment effect of accumulator pressure shell. The results show that the microstructure of 35CrMo steel shell after overall quenching and tempering was tempered sorbite. The magnetic field intensity and its gradient increased obviously after heat treatment. The coercivity increased from 749 A/m to 1 025 A/m, and was linear with hardness. The coercivity of available materials effectively characterized the hardness and strength of accumulator pressure shell.