To meet the power requirement of small high altitude aircraft

the intake and exhaust system flow uniform of a aircraft piston engine was analyzed. Simulation model of the aircraft piston engine was established

and the effects of intake and exhaust pipe structural parameters on engine performance were analyzed. The intake mass flow unevenness and pressure fluctuations were chosen as evaluating indicators to optimize the structural parameters of the engine's intake and exhaust system. By changing the length of intake manifold and duct

the unevenness is reduced to less than 5%

and the biggest decrease amplitude is 38%; the engine power and torque are improved by 5%.