The invention provides a virtual synchronous power generator-based fault ride-through control method and system. During a power grid fault, a DC/DC converter of a virtual synchronous machine is switched to a constant-voltage and feedforward control mode from a constant-voltage control mode, a first current instruction value is obtained by subtracting a voltage instruction value from a voltage feedback value and by PI regulation, a first voltage value is obtained by subtracting the first current instruction value from a current feedback value and by PI regulation, the DC/DC converter is controlled, a DC/AC converter of the virtual synchronous machine is switched to a current-constant control mode from a VSG control mode, a reactive current is obtained by reactive voltage regulation control,an active current is calculated according to the reactive current, and the DC/AC converter of the virtual synchronous machine is controlled according to the reactive current and the active current which are obtained by calculation. By mode conversion of a virtual synchronous power generation system and control strategy optimization, fault ride-through of a station-type virtual synchronous power generator is achieved, and the stability of a power system is ensured.