A surface navigation platform model needs to conduct self-propelled test in open water, and the experimenters need to control the four thruster motors and four rotary motors of the model on shore, so as to control the movement of the model. Because the model is small in volume and can carry small weight.Aiming at this problem, a set of simple structure and low cost control system is designed.The system is based on Modbus RTU protocol and controls the motor through serialport. The actual test result shows that the system can control the rotation speed and angle of the servo motor in real time,the maximum control distance is about 1km, and the control error is within 3%, which shows the system can meet the needs of the test.