The internal flow passage of centrifugal pump involves many geometric parameters and area parameters, which are not independent but interrelated. Area ratio is a physical quantity which combines different area parameters together, and studies the area ratio relationship between the impeller outlet and the inlet, which can provide new ideas and methods for the improvement and optimization of centrifugal pump. In this paper, through numerical calculation, the hydraulic performance, flow characteristics and pressure pulsation characteristics of centrifugal pump under different area ratio parameters are compared. The results show that when the area ratio increases, the head and efficiency of the pump are better, and the flow excitation under the main excitation frequency decreases. In addition, the recommended area ratio value range is also given.