Combustion characteristics and working performance of the blending hydrocarbon fuels in a micro combustor are investigated. Experiments and simulations are conducted to analyze the effects of CH4 and C3H8 blending on the premixed H2/air burning process and wall temperature distribution. To enhance the radiation power and energy conversion rate of the micro thermophotovoltaic (TPV) system, the combustors inserted with varied fins are proposed and compared. The results indicate that the premixed H2/air combustion with 7.5 % CH4 addition gains the best thermal ability due to the flame location modification and reaction zone extension. Nevertheless, the combustion with 5 % C3H8 blending achieves the highest wall temperature in C3H8/H2/air burning. Moreover, the CH4/H2/air combustion gains a better thermal performance than that of C3H8/H2/air burning under the same blending ratio owing to the descending heat loss from the outlet and enhanced reaction intensity. The reaction pathway and sensitivity analysis demonstrate that the chemical reaction rate related to the OH radical is reduced with the CH4 or C3H8 blending ratio, leading to the stretched flame. The reaction rate of CH4/H2/air combustion is higher than that of C3H8/H2/air, increasing the heat release. Besides, the inserted fins optimize the fluid field and enhance the heat recirculation, then a higher radiation temperature is obtained. The combustor with appropriate fins number and length effectively achieves a satisfactory working performance. In particular, the highest radiation efficiency of 54.0 % and highest radiation power of 69.1 W are obtained in the combustor C8-24 burning with 7.5 % CH4 under chemical energy Ec = 91.5 W and Ec = 141.4 W, respectively.