Abstract: Effects of material and technology factors including forging ratio,pre-treatment,carburizing temperature,carbon potential,quenching temperature and preheating,etc on the heat treatment distortion of 20CrMnMo steel were studied by orthogonal test.The result shows that the effect on the distortion of pre-treatment,carburizing temperature,carbon potential and quenching temperature is very prominent;the effect on the distortion of forging ratio and preheating is inapparent,but they have favorable effect in the optimized technology;According to the distortion characteristic of 20CrMnMo steel during carburizing and hardening process,the distortion of 20CrMnMo steel would be controled preferably via optimized technological parameters.The minimum distortion is 0.08 mm.