Operational and reliability problems may rise when a large amount of wind and solar power penetrate into power system, due to the characteristics such as volatility and randomness of these renewable energies. In order to assess the operation status and reliability of the hybrid power system, it is very important to establish a set of indices to evaluate the performance of the hybrid power system operation. In this paper, firstly, the existing indices are analysed. Then, three new indices such as output offset rate, output offset coefficient and output relative coefficient are proposed for measuring the power output. Finally, the proposed method with three new indices is used to analyse the power output of the wind-solar hybrid system in the specified time period. The results show that the proposed indices have great practical significance and outstanding simplicity, and can effectively evaluate the operation status of the hybrid power system comparing with the traditional indices.