Swing system is the core unit of pumping machinery,its performance directly affects the performance of concrete pump machinery.Aiming at the problems of motionless and slow swing of swing system,the working principle of swing system was analyzed,the mathematical model of accumulator charging and discharging oil and swing pressure loss was established,and the influencing factors of swing pressure loss were analyzed.The simulation model of swing system was established based on AMESim platform,and the influences of the structure of the swing valve block and the accumulator parameters on the swing performance were discussed.The structure of the swing valve block was optimized,which makes the reversing time of the swing cylinder decrease from 198 ms to 166 ms.The feasibility of the optimization scheme was verified by experiments.