By utilizing the numerical solution and Finite Element Analysis (FEA) approach, the effect of the air gap beneath a heating membrane on the performemce of a micro heater was calculated and simulated. The thermal convection coefficient was acquired from a heating experiment. Then, a 1D Fourier heat transfer equation was derived.By using the Biot number calculated and the lumped-capacity solution, the model was simplified into a multi-layer thin slab one.Furthermore,the transient temperature response and stable thermal distribution of the air gap in thickness of 0 (pure Si substrate), 100, 200, 300, 400 μm and completely through (heating membrane) were compared under the conditions of heat convection and heat transfer. Calculation results show the climax temperature has increased approximately 17% by utilizing the heating membrane structure. The results of steady state and transient thermal-electrical coupled field FEA reveal that 200 μm air gap structure indeed enhances the climax temperature to 390 K and reduces the power consumption to 134 mW, which is coherent with the numerical calculation results and experiences.