Abstract: In order to predict the distribution of residual stress of 20Cr₂Ni₄ steel in pre-stress turning, a 3D finite model was established based on equivalent loading theory to transfer the cutting process into a combined cycle effect of contact normal stress, tangential stress and heat flux. The shape and value of equivalent thermal-mechanical loadings were extracted from analytical model of cutting force and heat. The simulation results of residual stress distribution are basically consistent with the measured results. Analyzing and comparing the simulation results, the influences of cutting speed, feed rate and pre-stress on residual stresses distribution were studied. These results show that the effect of cutting speed on residual stresses distribution is not obvious. With the decrease of feed rate, surface residual tensile stress and the maximum compressive stress decrease accordingly. Moreover, the increase of pre-stress leads to the decrease of surface residual tensile stress and the increase of the maximum compressive stress.