Abstract: The effect of heat treatment on microstructure and properties of a new-typed low nickel austenitic nonmagnetic steel were analyzed by observing microstructure, tensile testing and magnetic property testing. The results show that the precipitation phase in the steel was fine and dispersive after solid solution at 1 150 ℃ for 1 h and aging at 750 ℃ for 4 h, the tested steel could own good mechanical properties and low permeability, and the yield strength was 637 MPa, tensile strength was 1 134 MPa, elongation was 36.8% and permeability was 1.254 × 10-6 H·m-1.