The purpose of this resaerch is to discuss the influence of exhaust's Engine muffler inside diameter of the first chamber communicating changes in the third chamber, exhaust fluency changes The experiment observes the variation of inlet and outlet resulting from diverse exhaust measurements of four-wheel 600 C.C. capacity ATV. The methods adopted is to use Pro/E analysis software to draw simplized patterns and then design the exhaust sample for further testing and analysis. The results reveal that exhaust's construction transforming has evident effect on the flow of exhaust emission of vehicle as well as output performance of engine and suggest to carry out integrated evalution concerning engine construction design and commercialize production.