Different limitations exist in the practical application of one-dimensional and three-dimensional methods on the acoustic simulation of muffler respectively. Thus, a hybrid one/three-dimensional approach is developed in present paper to carry out the acoustic simulation of muffler matching with the engine. The acoustic source characteristics of engine are computed with one-dimensional methods, and acoustic four pole parameters of muffler are computed with three-dimensional methods, respectively. And, the insertion loss of muffler is finally calculated. The insertion loss of a muffler equipped with Selective Catalytic Reduction (SCR) in a heavy duty vehicle is simulated. The numerical results agree well with the experimental results, which verifies the reliability and accuracy of the present approach.