After a fault occurs in the AC power grid, the photovoltaic (PV) DC grid-connected system (PV-DCGS) needs to enter the low voltage ride-through (LVRT) mode and reduce the active power of PVs to avoid DC bus overvoltage. However, when the grid voltage drop is deep, the control loop switching of the PVs can cause current backflow, and even damage to the PV panel. Therefore, this paper proposes an AC fault active power control strategy for PV-DCGS based on power self-feedback iteration. Using the PU characteristic curve of PV, an iterative formula of the port voltage reference value is constructed, and the reference value is updated according to the output power feedback of PV. At the same time, the distribution scheme of single-machine maximum utilization is proposed to rationally select the PVs that could participate in the power control task. The advantage of the proposed method is that it does not need to cut off the control loop of the PVs, and it can reliably calculate the port voltage reference value of the PVs. Simulation verification shows that the proposed method can reduce active power in the system and reduce the current fluctuation on the low-voltage side of the DC converter of PV during the PV’s mode-switching process, providing a guarantee for the reliable implementation of LVRT in the system.