In order to study the influence of operating parameters on blood pumps performance and shear stress,the internal flow of blood pumps was photographed using high-speed photography,and the shear stress in the pumps was simulated numerically.A visualization experiment method was established to observe the flow in the blood pump,the variation law of the external characteristics of the pump with the impeller speed and blood flow rate was revealed,and the influence of the pump structure and operating parameters on the shear stress was also clarified.The research results show that the high shear stress in the pump is mainly distributed in the volute tongue and blade tail,reducing the rotational speed and increasing the flow rate can effectively reduce the shear stress in the pump.Comparing the experimental results with the simulation results,it is found that the fluid trajectory is consistent,and the external characteristic error is within 6.9%.