The regulator is a critical component utilized to alleviate the turbulence in the internal flow field.The hydraulic performance of regulator is of great significance in improving the stability of flow.Thus,the starshaped regulator employed inside the firefighting monitor was taken as the research object and the threedimensional model of fluid filed was built as well as the finite element model,then the simulation parameters were identified.The proposed indexes to evaluate the hydraulic performance of regulator were pressure loss and flowstraightening performance.The influence factors such as the number of uniform distribution blade,the size of round angle and the length of regulator were analyzed by the simulation.To improve the hydraulic performance,the regulators with different numbers of blades were simulated respectively.The simulation results indicate that the one with 6 blades has better performance,which is validated by the experimental testing.The study provides references for the researches on the hydraulic performances of regulators.