Blood pumps are medical devices that can temporarily or permanently replace the heart to perform the job of blood pumping. To study the internal flow field characteristics of the centrifugal blood pump, high-speed photography (HSP) images of the internal flow in the centrifugal blood pump were taken, and the internal flow field was numerically simulated. According to the heartbeat rule, the visualization experiment method and numerical simulation method for the internal flow of the centrifugal blood pump were developed. The internal flow rule of the centrifugal blood pump during a heartbeat cycle was revealed, as well as the influence of pump construction, flow rate, and other factors on the pump’s flow field. The results indicate that the flow rate and the rotor/stator interference of the blade and volute tongue cause two periodic changes in the pump pressure and velocity. One is the cycle of the heartbeat, and the other is the cycle of the blade’s rotation. The research results are of great significance in reducing the mechanical damage of blood, optimizing the structure of the pump and improving the stability of the centrifugal blood pump.