In the short process of casting-rolling continuous forming of ring blank, cracks are likely to occur on the surface and corners of casting ring blank at high temperature. The effect of the wall thickness of 42CrMo centrifugal casting ring blank on crack formation was discussed by Procast simulation, and some effective measures to control crack were put forward. The simulation results show that the main causes of crack formation are large thermal stress and strain, due to the uneven distribution of high initial temperature and large temperature difference with the environment, and in order to avoid the formation of cracks, thin-walled ring blank with an outer diameter to inner diameter ratio of about 1.5 should be selected. The inner wall of metal is covered with sand and the die is designed with rounded corners, which can reduce the local stress concentration of high-temperature ring blank and reduce crack sensitivity. The research results can provide important theoretical guidance for the realization of innovative processes.