The invention provides a compensation method of primary frequency modulation capability of flow dynamic non-linearity of high valves of a steam turbine, and relates to the technical field of primary frequency modulation capability compensation of flow dynamic non-linearity of high valves of a steam turbine. The compensation method of primary frequency modulation capability of flow dynamic non-linearity of high valves of a steam turbine solves the problem that the flow dynamic non-linearity of the high valves of a coal-fired steam turbine causes the effect that the practical diversity factor of the rotating speed of the steam turbine is greater than a set diversity factor of the rotating speed. The compensation method of primary frequency modulation capability of flow dynamic non-linearity of high valves of a steam turbine can guarantee that the generation power changes 20% through primary frequency modulation when the rotating speed changes 1%, by modifying the diversity factor setting specifically according to an active power instruction and a primary frequency modulation factor, and can guarantee that the generating set of the coal-fired steam turbine has a certain primary frequency modulation capability. The compensation method of primary frequency modulation capability of flow dynamic non-linearity of high valves of a steam turbine is suitable for compensation of primary frequency modulation capability of the subcritical coal-fired steam turbine generating set.