In order to solve the problem of the lifesaving robot to achieve fast and stable navigation, the 3D inverse design theory is used to obtain the geometry of the robot pump. Under reasonable assumptions, the swirl equation in the water jet pump is effectively decomposed to obtain the circumferential mean flow equation and periodic fluctuating flow equation. The distribution of speed moment along the streamline is used to control the loading on the blade, and the hydraulic performance of the designed water jet pump is calculated by computational fluid dynamics. The results show that the hydraulic efficiency of the water jet pump reaches 80.38% under the constraints of large hub diameter ratio and other specific conditions. At the same time, it maintains high efficiency in a wide flow range. The pressure distribution along the axis of the impeller surface is reasonable, and low pressure zone is not found, the impeller thrust meets the expected value, which proves the design and parameter configuration are correct and feasible.