In order to improve the modeling accuracy of a PV system, a method of making full use of the LVRT test data to establish a PV model is studied. A 500 kW photovoltaic unit of a photovoltaic power plant in Inner Mongolia is taken as the research object. First, based on the typical LVRT control strategy, the parameter identification of the LVRT control link is completed by the least squares estimation method. Secondly, the environmental parameters of PV arrays are obtained by modifying the PV characteristic curve. Finally, the calculation process of array parameters and the identification process of the LVRT control strategy are designed, and four groups of measured data with different voltage sag levels are selected for identification. After substituting the identification results into the simulation model based on Simulink, the validity of the proposed method is verified by comparing the simulation results with the measured data. This work is supported by Natural Science Foundation of Hebei Province (No. E2018502134).