Permanent magnet synchronous machine (PMSM) with fraction-slot concentrated-winding (FSCW) is popularly applied in the field of aerospace and electric vehicle for its good flux-weakening capability, low cogging torque, and high torque density and efficiency. This paper mainly focuses on the PMSM-FSCW used for airborne radar servo system. With the magnetic circuit characteristics of PMSM-FSCW, the analytic model of the motor is established. Influences of some design parameters, such as number of poles, ratio of length to diameter, split ratio and magnetic flux density coefficient on the motor performance are studied. Analytical results show that output torque and weight of the motor are respectively proportional to the outer diameters of stator, D_os³ and D_os²,and the percentage of coil end to whole windings is inversely proportional to the ratio of stator length to its outer diameter λ. In view of torque density and percentage of coil end mentioned above, the value of λ is recommended from 0.2 to 0.4. When split ratio γ, i.e. the ratio of stator inner diameter D_is to outer diameterD_os, raises, output torque firstly increases and then decreases. Hence the γ is advised to select in the range of 0.6-0.8 for the maximum torque density. When the ratio of the largest flux density in the stator iron core to air-gap flux density χ enlarges, output torque firstly increases and then decreases. χ should be designed at about the value of 1.75 for the maximum output torque. Based on the theoretical analysis and simulation results above, a prototype of PMSM-FSCM,with the combination of 45-slot/38-pole,is designed and manufactured, and its performance is experimentally tested.