Pre-heat treatment of MC5 steel cold roll after forging was investigated. The results show that, by the conventional process, the carbide network structure and carbide particle size of the roll is 3 grade and over 2 μm respectively, which can't meet production requirements. The reasonable process parameters 1050 °C high temperature heating and quenching and 740 °C tempering are determined based on the equilibrium phase diagram calculated with Thermo-calc thermodynamics software. After treated by the new process, the microstructure is uniform...