To research the influence of combustion chamber thermal boundary conditions on micro combustion characteristics in micro ICE, the laminar flow finite rate model is adopted to simulate the micro combustion process. Firstly, the influence of grid scale, the time step length and the maximum iterations per time step on accuracy of simulation results are explored. The results show that simulation results agree well with experimental results. And then, the influences of heat transfer coefficient, wall thickness and material on combustion characteristics are discussed. The results indicate that heat transfer coefficient has obvious influence on combustion characteristics. The pressure rise rate decreases, the ignition delays and the highest pressure value drops 2 atmospheres as heat transfer coefficient increases from 0 to 55 W/(m 2·K). The wall thickness and material have a little effect on combustion characteristics. This is because that the main heat transfer resistance in the heat flow path from cylinder to external environment lies between the outer wall and environment.