Abstract: In this paper, through the analysis on the primary frequency regulation performance of 1 000-MW double-reheat ultra-supercritical units, the major factors affecting the primary frequency response of double-reheat units are expounded from the aspects of furnace characteristics, control strategies and operation modes. Moreover, the impact of frequency modulation on the unit coal consumption rate using main steam regulating valve throttling is evaluated for a 1 000-MW ultra-supercritical double-reheat unit. Based on the feasibility analysis of throttling frequency modulation, condensate frequency modulation and feed water frequency modulation, the method to improve the primary frequency regulation capability of 1 000-MW ultra-supercritical double-reheat units is discussed in order to provide reference for the design and operation of the double-reheat units in the future.