Abstract: GCr15 steel balls were quenched at different quenching heating temperatures. The microstructure was characterized by optical microscope, SEM and laser confocal microscope. The content and hardness of residual austenite were characterized by X-ray diffraction and Vickers hardness meter respectively. The experimental results show that with the increase of quenching heating temperature, the flaky martensite structure gradually increases, the number of undissolved carbides gradually decreases, the particle size of carbides approaches the middle size (0.4-0.8 μm), the grain size of original austenite and the volume fraction of residual austenite gradually increase, and the hardness shows a trend of increasing first and then decreasing.