The effect of preheating was investigated in a straight-tube shape micro combustor. Performances of combustor were compared under conditions with different preheating temperature. The flow rates of the fuel feed amount were 0.12, 0.24, 0.36L/min, respectively. The preheating temperatures were environmental temperature (23℃), 250℃, 500℃, respectively. Experimental results showed that with environmental temperature and 0.12L/min, the stability limit was 0.339~3.639. While the preheating temperature increased to 250℃, the stability limit extended to 0.317~4.304. At the preheating temperature of 500℃, the stability limit was 0.453~1.706. The temperature distribution on the combustor wall was measured, which was combined with numeric simulation to investigate the combustion process in the combustor. Simulation results indicated that the peak temperature in the reaction region increased with preheating temperature. At 0.24L/min and stoichiometry, while the preheating temperature increased from environmental temperature to 500℃, the peak temperature increased from 1890 to 2013K. It proved that the proper preheating could increase the reaction temperature, thus inhibited thermal extinction. 