At present, most of muffler design methods are based on approximate theories, experiences and experiments. There are some disadvantages in the traditional design methods, which counteract the improvement of muffler. But an advanced method, named computer aid engineering (CAE), can avoid the disadvantages of these traditional methods. In this paper, the CAE analysis method is researched with software (GT-Power). The transmission loss model, the insertion loss model and the pressure loss model of the muffler were established. The property evaluation of the muffler was considered during the course of optimizing the projects. The evaluation method of muffler, CAE, was studied. The optimized project was trial-manufactured and the result of CAE analysis agreed well with the experimental result.