This paper has examined the hardening effect and mechanism of explosive working on high-manganese steel. According to the experiment result, the surface hardness of high-manganese steel is improved greatly after explosive working and the hardened depth exceeds 40mm. The surface hardness and hardened depth increase slightly, the tensile strength is improved and ductility is reduced after three times of explosion. Charpy impact test demonstrates that it has still high ductility, the fatigue performance isn’t inferior to that before the explosion, the abrasive resistance is higher than that before the explosion and macroscopic residual deformation is extremely small. Such changes are related with the internal stress and changes of metallographic structure after explosion. After explosion, the surface is at stress state and the metallographic structure still retains the single-phase austenite matrix; and it produces high-density dislocation, stacking fault, cross-slip, lattice torsion, twin-crystal and refinement of austenite crystal grains.