Reactive mufflers are generally evaluated by their aerodynamic performance and acoustical performance. In this paper, the CFD method was used to simulate the pressure distributions in the flow fields of three specified reactive mufflers with different structures. The pressure losses for the three mufflers were obtained. The results were compared with those by the semi-empirical formula. The aerodynamic performances of the three reactive mufflers were analyzed, and the suitability of the semi-empirical formula was evaluated. The AFEM (acoustic finite element method) was applied to calculating the transmission losses of the three reactive mufflers, and their acoustic performances were qualitatively analyzed and verified. This study provides helpful references for the structural optimization design and the performance improvement for reactive mufflers.