The invention provides an over-speed and variable pitch coordination-based variable speed wind turbine generator set primary frequency modulation method. The method comprises the following steps of: 1) providing a load reduction operation scheme for an variable speed wind turbine generator set; 2) determining that the variable speed wind turbine generator set operates according to the load reduction operation scheme; 3) judging whether the variable speed wind turbine generator set participates in system frequency modulation; and 4) activating a primary frequency modulation control module to enable the variable speed wind turbine generator set to participate in the system frequency modulation. With the method adopted, changes of the kinetic energy of a wind turbine are fully considered when active spare capacity is reserved, and the output capacity of the wind turbine itself can be effectively utilized; and when power?shortage occurs on a system, and the frequency of the system is decreased, continuous active power support can be provided, and improvement of the stability of the frequency of the power system can be facilitated.