The invention discloses a primary frequency modulation control method and system for a wind power plant. A wind power plant power distribution strategy by using overspeed load shedding control is used. The method comprises the steps that: after a wind power plant receives a system scheduling instruction, power requiring load shedding is calculated according to wind speed information fed back by all wind turbine generators, a power reference value and a load shedding control mode are distributed to all single machines, rotor kinetic energy of the wind turbine generators is stored to the maximumextent, and the frequency dynamic characteristic of a system is improved; and a variable parameter control strategy is utilized in frequency modulation control, the control strategy can ensure that afan can release the maximum standby power in the frequency modulation process, and the recovery speed after frequency drop is increased. It is guaranteed that each fan sufficiently releases standby power in the frequency modulation process, and a frequency steady-state value is effectively increased. The change of an inertia control coefficient can effectively improve the recovery speed of the frequency.