For a certain type of muffler, through the simulation software GT-Power, the equivalent distribution law of the coupling effect of the insertion tube muffler exhaust inlet diameter ( 43~63 mm ) and intake-tube diameter ( 38~58 mm ) on the piezoresistive loss of the muffler and the transmission loss under the equivalent piezoresistive loss were analyzed. The results show that the change rate of piezoresistive loss under the coupling of the inserted tube unit is larger in the area with higher and lower piezoresistive loss. In the influence of insertion tube unit coupling on the piezoresistive loss of the muffler, the larger the equivalent piezoresistive loss is, the larger the transmission loss range of the curve at medium and high frequencies is. In the region with small equivalent piezoresistive loss, the basic structural unit is more sensitive to the influence of equivalent piezoresistive loss. The greater the equivalent piezoresistive is, the greater the variation range of transmission loss is, especially in the middle frequency band 620~850 Hz. Finally, the evaluation system of comprehensive acoustic performance and aerodynamic performance was established, and the structural parameter combination area with better performance than the original muffler based on boundary conditions was found.