The change of internal flow field, wear position, wear quantity and conveying capacity of centrifugal pumps were explored at different inlet speeds(0.6, 1.2, 1.7 m/s) and rotational speeds(2650, 2800, 3000 r/min) by using the method of discrete element method and fluid dynamics coupling. The results show that the tail of impeller blade of centrifugal pump is prone to cavitation, and the influence of velocity on cavitation and retention area of outlet pipe is greater than that of speed. Under nine working conditions, the maximum abrasion loss of the centrifugal pump appears at the tail of the blade. When the speed changes from 2650 r/min to 3000 r/min, the most serious wear part changes from the tail of blade 1 and 4 to the tail of blade 1 and 2. The impeller blade is the most serious wear part of the centrifugal pump, accounting for 39.36%-49.41% of the total abrasion loss of the centrifugal pump. According to the average residence time of particles in the centrifugal pump under nine working conditions, the flow rate has a greater impact on the performance of the centrifugal pump than the speed, and the average residence time of particles under 0.6, 1.2 and 1.7 m/s are 0.144, 0.068 and 0.052 s respectively, which indicated that the centrifugal pump delivery performance improved with an increase in the velocity.