In order to accurately master the efficiency-improving and capacity-expanding potential of Baiyunxia hydropower station, and ensure that the technical transformation scheme has high safety, reliability , and economics of energy saving, based on the design ideas of mutual verification between analyzing the runoff data of reference station and back-calculation of the power generation, the hydropower-checking of the power station for mining the potential expansion has been done. The optimal installed capacity, scheme and turbine type of Baiyunxia hydropower station have been confirmed after considering the water flow of "Hongyanhe-to-Shitouhe Water Transfer Project" and reformed technical requirement of small hydropower. The research results show that through the calculation and back-calculation of Yingge station runoff data in Shanchahe and statistical data of years of running power generation, the accurate data of water energy index which can reflect the operation characteristic of power station has been obtained. And the optimizing selection and reasonable technological reform of the hydro-turbine can ensure the generator unit long-term operating in high efficiency operating area. After feasible technical reform the design objective of increasing the output and preventing the cavitations has been achieved, the power station can realize the aims of energy conservation and consumption reduction at the same time of efficiency-improving and capacity-expanding.