In order to optimize the layout and number of holes and geometric parameters such as the section shape, area, and outlet pipe diameter of the oil bath in hydrodynamic design of a runner-pump for the thrust bearing of hydroelectric units, a method for performance prediction and optimization design suitable for the flow passages of the runner-pump is presented in this paper. Through combination of different geometric parameters, the influence of the size and shape of the main flow passage components on hydrodynamic performance of the runner-pump was analyzed using the performance prediction method based on multi-condition numerical simulations. In this way, a hydrodynamic optimization design method for the runner-pump based on cooperation throughout the circulation system, which can improve the performance and reliability of the hydrodynamic system for self-circulating system design, is proposed. The results show that, compared with the original runner-pump, the average head is increased by 4m, the average efficiency is increased by 5. 5%, and the H-Q curve can guarantee better stability of the system under varying condition operation for the optimized runner-pump under the same test conditions.