Conventional design parameters of attitude control fly wheels motor are calculated repeatly based on experiences and the optimal parameters can not be acquired.On the basis of a circuit method and a Finite Element Method(FEM), this paper proposes a design method for the driving motor of an attitude control flywheel, in which the effective ratio of diameter to length is taken as a design core. The computing model for circuit design was established according to the relationship between the ratio of diameter to length and the parameters of the motor, then the air-gap flux density and the inductance were calculated by using FEM based on Laplaces equation. Finally, the calculated results were used for the accurate analysis of the performance of motor. Moreover, a hub driving motor in an attitude control flywheel with angular moment of 5 Nms was designed and its electromagnetics torque ripple and the mechanical characteristic were simulated. The results show that the regulating characteristics of theoretical calculation is in agreement with that of the experimental results well, and the maximum error of electromagnetic structure is 2.9%. It concludes that this method is suitable for the design of attitude control flywheel motors, and is characterized by higher speeds and good precises.