The mathematic calculation on two-body wear of austenitic manganese steel has been performed by means of the elastic contact theory, stress interferometer and SEM.Stress distribution in contacted area was calculated and the mechanism on two-body wear has been investigated through numerical quadrature. Results show that two-body wear is mainly plowing wear, the cracks of abrasive dust originates from the region between 0.2α and 0.5α (α is radius of contacted round). Driving force to make crack extension along y axis is Tyzmax and extension direction is 45° with horizon. Driving forces to make crack extension along x axis is alternative σx and Tyzmax, the direction of crack extension is 37° with horizon.