In this paper, through the study of traditional light bus, found problems related to screening and using existing methods, bridge drive of light bus was designed. First determine the drive axle transmission ratio and reasonable distribution; secondly on the driving axle main transmission device structure and parameter design, including the design of main reducer, differential, half shaft design; finally completed the design of driving axle housing, in order to design the drive axle complete. And the use of traditional mechanical analysis methods of main parts of the driving axle ( reducer, differential, half shaft, axle and so on) for the strength analysis and calculation, including the gear bending stress calculation, strength check; gear contact stress calculation, strength check; half shaft torsional stress calculation. With the design idea and the design requirements of the rapid development, the three-dimensional design has become a necessary skill for designers, this paper introduces the basic functions of Pro/Engineer software and a simple application, and the design of the parts of the drive axle using the software.