As the development of microprocessors, power electronic converters and electric motor drives, electric power steering system which uses an electric motor came to use a few year ago. Electric power steering systems have many advantages over traditional hydraulic power steering systems in engine efficiency, space efficiency, and environmental compatibility. This paper deals with design and optimization of an interior permanent magnet motor for power steering application. Direct search method is used for optimization. After optimization and finding motor parameters, an interior permanent magnet motor and drive with mechanical parts of electric power steering system are simulated and performance evaluation of system is done.