Abstract: The experimental study with different cold rates and different tempering temperatures after austenization of ZG20SiMn steel was carried. The microstructure and mechanical properties of the steel were characterized using metalgraphic analysis and mechanical properties test. The results show that, after quenching of ZG20SiMn steel, the ferrite content in the matrix is greatly reduced and bainite increases, the strength, hardness and plastic toughness of ZG20SiMn steel are greatly improved. The mechanical properties of ZG20SiMn steel can meet the requirements very well.