In order to save energy and protect environment, above all ,to adapt to the requirement of the future city traffic, a new multifunctional, high efficient and integrated motorized wheel system for electric vehicle including in-wheel motor, brake and semi-active suspension was proposed .The project of directly driven electric wheel system was formed. Some essential performance indexes of electric vehicle considering the traffic condition and environment of city road were studied, and then the power indexes and structure of in-wheel disc permanent magnet motor were determined. In addition, the semi-active suspension in wheel based on magneto-rheological fluid damper (MR damper) was designed. Finally, simulating model of 4WD electric vehicle with motorized wheel system were constructed by using the simulation software ADVISOR, then the vehicle dynamics simulation was carried out under the test condition, results show that, the dynamic performance indexes can adapt to the city traffic, the design of motorized wheel driving system is practical and feasible.