Abstract To simulate and analyze the control rod ejection time in the process of reactor bomb rod accidents, the design input of bomb rod accident safety analysis is made. In this study, STAR-CCM+ simulation software was used to simulate the pressure field and velocity field in the process of high temperature and high-pressure liquid injection after the CRDM pressure casing was broken, and the ejection time of the control rod under different lifting forces was obtained comprehensively. At the same time, the simulation results are compared with the theoretical calculation results. The pop-out time of the control rod is about 0.1 s. Therefore, the results calculated by the simulation model established in this study can be used as the design input for the safety analysis of the projectile rod accident.