Abstract: Aiming at the problem that the insertion loss of an automobile exhaust muffler has not been up to standard, a coupling simulation model of coupling between the engine and the intake and exhaust system is established by GT-Power software. The acoustic performance and aerodynamic performance of the exhaust muffler are calculated numerically. The insertion loss and pressure loss are analyzed at an engine speed range between 1 000 and 2 500 rpm. According to the analysis results, a multi-condition, multi-parameter and multi-objective optimization is conducted to the muffler structure based on the DOE (Design of Experiment) method. The optimization results indicate that the insertion loss of the optimized muffler is obviously promoted, the aerodynamic performance is satisfactory, and its comprehensive performance is significantly improved.