Abstract: A calculation model and evaluation index of the ratio of wind power, photovoltaic power and solar thermal power were established. Seven matching schemes were worked out, and the typical daily load curve of Inner Mongolia power grid in summer and winter was taken as the optimization objective. The calculation model and its evaluation index were used to calculate and analyze the matching schemes. The results showed that, based on the calculation of basic parameters, the scheme with the ratio of 150 MW for wind power, 50 MW for photovoltaic power and 100 MW for solar thermal power had better power quality and grid operation stability. At the same time, the system had better overall delivery capacity, which could effectively reduce the waste of wind and light.