The invention discloses a variable speed wind turbine generator participation system frequency modulation method. The method comprises the steps that firstly, a wind turbine generator group is grouped to obtain multiple wind turbine generator sets; the frequency control dead zone and system frequency offset of each wind turbine generator set are set; then, when the system frequency offset exceeds the frequency control dead zone, wind turbine generator frequency control is triggered, and the frequency modulation operation mode is entered; the frequency modulation increment and frequency modulation time sequence of each wind turbine generator set are calculated; the frequency modulation increment and the frequency modulation time sequence are issued to each wind turbine generator set; finally, whether the system frequency of each wind turbine generator set exceeds the minimum point or not is judged; if yes, the wind turbine generator set exits from the frequency modulation operation mode; if not, according to the frequency modulation time sequence, frequency modulation operation is performed till the end. According to the variable speed wind turbine generator participation system frequency modulation method, on the basis of the wind power plant participation system frequency modulation time sequence control strategy, the wind turbine generator sets are coordinated for frequency modulation active power increment and time sequence exit, and the potential of variable speed wind turbine generator participation system frequency modulation is sufficiently excavated.