Abstract: With the increasing penetration of renewable energy resources in the power system, the frequency regulation requirements of the power grid and thermal power units are getting higher and higher. Energy storage can relieve the pressure on frequency regulation of the power grid and unit, but there are no effective methods to evaluate the frequency regulation process of energy storage. A comprehensive performance evaluation method for combined thermal-energy storage frequency regulation based on improved weight factors is proposed. To ensure the objectivity and rationality of the distribution of weight factors, the frequency regulation performance index system is reconstructed, and the subjectivity problem of experts is fundamentally solved by introducing the relation analysis and the entropy weight method. The fuzzy judgment matrix is constructed by using the method of adapting fuzzy method to time scales, and the quality of regulation process is comprehensively evaluated by criteria of the principal component analysis. The experimental results show that the proposed method can effectively judge the adjustment performance of frequency regulation with different time scales, and help energy storage system establish auxiliary compensation standards to participate in the frequency regulation of the power system.