A motion control structure with a distance fuzzy controller and an angle fuzzy controller is proposed to determine velocities of the left-wheeled motor and right-wheeled motor of the two-wheeled mobile robot. A PSO-based method is proposed to automatically determine appropriate membership functions of these two fuzzy systems so that the controlled robot can move to any desired position effectively in a two-dimensional space. A ratio coefficient coding method and a variable fitness function are considered in the proposed PSO-based fuzzy controller design method so that the proposed PSO-based method with a good searching efficiency and the selected fuzzy controller with a good control performance.