ESP hydraulic system is an important actuator for the active safety control system of vehicle. In the Matlab/Simulink environment, the real-time simulation model of ESP hydraulic system, which contains unknown characteristic parameters, is established on the strength of its structural principle. In order to identify the unknown characteristic parameters, several test cases that cover passive and active pressurization modes of the model are executed in the real vehicle experiment environment, and the collected vehicle measurements are divided into two groups. The unknown characteristic parameters of the model are identified with genetic algorithm by using one group as reference data. The model is compiled and downloaded to the real-time simulation system, which is named dSPACE AutoBox. Using the valve currents and pump motor signals of another group of measurements as the inputs of the model, the brake wheel cylinder pressures of the same group of measurements are compared with the outputs of the model. The results show that the real-time simulation model of ESP hydraulic system with the identification results of characteristic parameters has high accuracy, and can meet the requirements of establishing hardware in the loop simulation test environment for ESP system.