Abstract: Considering the randomness of photovoltaic(PV) power generation, issues such as insufficient primary frequency modulation(FM) performance and grid frequency instability occur in different PV power stations. And the primary FM capability of PV station is the key to maintain grid stability, so it is of great significance to test and evaluate the primary frequency regulation capability of PV power plant. Taking an example of a PV-VSG photovoltaic power plant unit in Shichengzi, the significance, principle and measures of the implementation of primary FM in power station are introduced in detail, and a primary FM test technical scheme and experimental method suitable for the PV power station is proposed. Evaluation of PV plant security and stability is done by the disturbances of frequency step and simulation of actual grid frequency, calibration pass rates of anti-disturbance performance and AGC coordination, and it has practical application value and promotional significance.