Electric power steering system (EPS) is a new power steering technology for vehicles. It has been used to replace traditional hydraulic power steering system (HPS). In this paper, an optimal control modeling and simulation design is presented for the column assist type EPS system with a brushed motor based on Matlab. Assisted characteristic chart of the system and block diagram of EPS are presented. The electric motor current is closed-loop controlled by analog PD and adjusted through altering the voltage over the motor by the technique of PWM. The results of simulation and analysis show that the model reaches a fine controlling effect, and the system designed has good following nature, quick response and high precision.