Abstract: The thesis gives a thorough theoretical analysis on electro-hydraulic load simulator,builds up loading system mathematical model, shows all the factors which affect the performance of load simulator,analyzes the effects of structure parameters to the frequency characteristics of the loading system by simulation.The results prove that the enlargement of load stiffness and leakage coefficient of loading system and the decrease of motor displacement and the total compressed volume can enhance the response velocity.So rational selection of structure parameter of loading system becomes the key to enhance the load simulator performance.The analysis results can provide the theoretical bases for developing the load simulator with high performance.