Electric Power Steering (EPS) is a full electric system, which reduces the amount of steering effort by directly applying the output from an electric motor to the steering system. This research aims at developing EPS boost curve embody into the assist characteristics, improving steer portability and stability. A model for the EPS system has been established, including full vehicle mechanical system, EPS mechanical system, and EPS electric control system. Based on this model, a straight line boost curve was designed and evaluated in this environment to improve the performance of EPS system. Results showed that EPS system with the designed boost curve improved light steering feeling and increased vehicle’s steering stability, and can meet the requirements of steering performance.