A new type of electric force load system was designed. This structure turns torque into force through ball screw pair to complete force load on the tested. The composing structure and the working theory of the load system were given, and a mathematical model of the load system was built. Proportion Integration and differential (PID) control and composite feedforward control strategy based on structure invariance principle were adopted for the system design. The simulation results show that the system can completely meet the requirements of the test index. This system compared with the traditional force load system, has advantages low moment of inertia and low load motor power, and can give a certain reference value to engineering practice.