In this paper, the bouncing phenomena of Free Piston Linear Generator (FPLG) and its influence on dynamic and combustion performance of FPLG during the starting process have been investigated. Using Simulink, FPLG was simulated by injecting compressed air at the combustion chamber and the piston was allowed to expand until bouncing phenomena occurred. The inlet pressure of compressed air was varied and it was found that the combustion pressure and frequency of FPLG increased when the inlet pressure increase. At higher inlet pressure, the FPLG shows to have advantage in term of combustion performance in comparison to low inlet pressure. © 2018 Author(s).