Abstract: For the needs of the experiment of matching performance of opposed-piston two-stroke engine, the software package of GT-Power was used to establish the calculation model of matching simulation for opposed-piston two-stroke engine and Rotrex supercharger, and in different cases the effect of exhaust back pressure on the gas exchange process was analyzed. The result shows that the engine can be well matched with the supercharger. At the same speed, the affect of exhaust back pressure on the scavenging efficiency is smaller. The speed is higher, the supercharger consumed power is bigger, accounting for 21%~25% of the engine effective power. When capture rate is more than 98%, the scavenging efficiency will be significantly reduced.