The composing and the function of every part of hardware-in-the-loop simulation system of steer-by-wire technologies on wheel loader were presented. The proportional relief valve to simulate the load of the system was introduced. Making use of the means of transfer function, the mathematics model of the system was built, and with the model, the system has been simulated, then the PID parameters in Matlab were regulated. An experiment was carried out on the hardware-in-the-loop simulation system to test the response with different input signals and loads. The result showed that it is well simulated the load by means of proportional relief valve, validated the feasibility of the use of steer-by-wire technologies on wheel loader.