An air-cored U-type permanent magnet linear motor is designed in this paper to simplify the structure of the missile steering system, reduce the connection cables and improve the reliability. The motor employs double side cambered PMs as excitation, and the air-cored coils directly drives the rudder blade. By canceling the reduction gear, the transmission efficiency of the steering system is enhanced. Moreover, the air-cored actuator can improve the response performance due to its light mass. The analytical thrust is derived in this paper. By comparing with the finite element simulation, the accuracy of the analytical formula is verified. The transient calculation shows that the designed direct-driven actuator can achieve the expected thrust theoretically.