The invention discloses an optimal system cost benefit-based heat storage proportion analysis method of solar thermal power generation. Power system benefit of the solar thermal power generation is analyzed on the basis of full consideration of solar thermal power generation characteristic, power grid running characteristic and load characteristic, quantization is performed by running simulation, and a reasonable heat storage proportion relation of solar thermal power generation is determined by comparing and analyzing a system benefit index, and the value of the solar thermal power generation in the power system is fully developed.