The low-order frequency noise dominates the exhaust noise, which has a significant influence on the exhaust noise quality. The dual mode muffler has a good control effect on the low-frequency exhaust noise, but there is still lack of in-detail analysis of the acoustic characteristics and fast design method for practical application. In this paper, a simplest model of a dual mode muffler structure was established. Through three-dimensional numerical simulation, it is found that the muffler owns an important low-frequency noise reduction peak, and the peak frequency shifts to high frequency direction when the valve opening increases. The chamber with the function of low-frequency noise reduction was determined through the analysis of sound pressure nephogram. The acoustic parameters of the valve in the dual mode muffler were extracted through the one- dimensional/three- dimensional hybrid simulation method. And the prediction model for acoustic characteristics based on lumped parameters was established for the resonant cavity part of the dual mode muffler. The simulation analysis shows that the sound inertial impedance of the valve body, which varies with the valve opening, is the key factor influencing the shifting direction of the resonance frequency. A dual mode muffler matching a vehicle was designed by the lumped parameter prediction model, and the correctness of the design parameters was verified by numerical simulation and transmission loss experiments. At last, a real vehicle road test was carried out. The test results show that the dual mode muffler of the matching design can greatly reduce the fourth-order exhaust noise, which validates the effectiveness of the proposed forward matching design method.