Abstract: Due to the problems of large unit vibration and serious wear of overcurrent components in Shaping Hydropower Station for many years of operation,it is necessary to increase the capacity of the units to improve the safety and annual power generation of the power station.In this paper,according to the layout of the water diversion system,based on the mathematical model of unit output and combined with the measured data of the power station,the actual roughness of the water diversion system under stable conditions is calculated. The results show that the average deviation between the measured values and the calculated values of the surge chamber water level and the turbine head is less than 0.9%,which proves the accuracy of the numerical model and the feasibility of the roughness adopted. In the case of keeping the size of the original hydraulic structure and foundation pit unchanged,the runner diameter increases from 2.03 m to 2.10 m,which is feasible to increase the total capacity of the station by 5%.The maximum and minimum surge water levels of surge chambers with load loss or load increase can still meet the design specifications of surge chambers and the existing elevation layout requirements. Therefore the capacityincreasing transformation of Shaping Hydropower Station is feasible.