Based on the real time digital simulator（RTDS）， a low voltage ride-through（LVRT） real time digital simulation scheme is presented for the photovoltaic generation system. A set of LVRT simulation platform including the voltage sag generator， photovoltaic array， isolation transformer and photovoltaic grid-connected inverter， is built by RTDS big step models and small step models. A LVRT control strategy is designed to ensure the photovoltaic grid-connected inverter operate in three-phase grid voltages normal and symmetrical drop conditions. Finally， the LVRT simulation test and field experiment have been carried out for a 250 kW photovoltaic grid-connected inverter. The simulation and experiment results show that the RTDS simulation platform is able to simulate the on-site testing platform and the proposed control strategy has good dynamic as well as static characteristics in LVRT process.