Abstract: Aiming at the problems of output current peak exceeding limit, AC side power fluctuation and DC side voltage instability in photovoltaic system under asymmetric grid fault, this paper proposes a reactive power support control strategy for photovoltaic gridconnected inverter under asymmetric grid fault. Taking the reactive power support requirement as the goal, the active power safe operation area of the inverter is determined with the active power fluctuation amplitude and the output current peak as the constraint conditions, providing sufficient reactive power support and expanding the active power output capability, or providing partial reactive power support according to the reactive current weight within the constraint conditions to ensure the safe operation of the photovoltaic system in the event of an asymmetric grid fault. Finally, the simulation verifies the effectiveness of the control strategy.