In order to solve the problem of high pressure impact which caused the weight swinged from side to side for a long time when the crane was on the slewing brake,the simulation model of slewing brake system was built using AMESim software. Then the pressure impact was analyzed and the technical parameter of the slewing damping valve in the system was optimized.The performance of slewing brake damping before and after optimization was compared. The simulation results and test data show that:reasonable design of technical parameter of the slewing damping valve can reduce the pressure impact of hydraulic system and improve crane efficiency.