This paper presents the design and modeling of a permanent magnet spherical actuator which consists of a rotor with eight cylindrical permanent magnet (PM) poles and a stator with twenty-four air-core coils. Torque and dynamic model of this PM spherical actuator are formulated analytically. An optimal design procedure is proposed to achieve a high torque output, and significant design parameters of the actuator are discussed. As there is no effective method for three dimensional orientation measurement of the spherical actuator currently, a novel orientation measurement system is proposed. Finally, experimental works are carried out, and the experiment results demonstrate the effectiveness of the proposed orientation measurement system.