Abstract: In order to study the characteristics of ultra-low-concentration gas regenerative combustion and its key influencing factors, a porous media combustion test platform was built. The characteristics of ultra-low- concentration gas combustion and its combustion stability has been investigated under different porosity porous media regenerators and their combinations. Results show that the combustion mode of ultra-low-concentration methane based on porous media includes surface combustion and submerged combustion state. Under the same burning conditions, the flame propagation speed of the surface combustion is lower than that of the submerged combustion. When the flame propagates in the pores of the porous media is higher than the gas axial flow velocity, the combustion mode of ultra-low concentration methane will transit from surface combustion to submerged combustion. And, the critical conditions for the transition of the combustion mode are determined on this basis. Unstable combustion characteristics such as combustion stratification, hot spots and combustion zone rupture are usually coupled with each other and evolve continuously during the flame transmission process. Also, their formation and development are closely related to the flame propagations and heat waves. The stable combustion wave can be propagated in the porous medium only when the critical criterion number (Bekeley's number) Pe≥65. Under present experimental conditions, 20PPI porous medium is suitable to the stable combustion for the ultra-low-concentration gas. Based on the above results, a new self-heating regenerative by the flue gas counterflow for strengthening intake-air preheating is proposed. Compared with non-heat recovery, flue gas counterflow can significantly strengthen intake air preheating and effectively improve the heat storage of ultra-low concentration gas combustion. It makes the temperature distributions in the porous medium much more uniform, and significantly reduces the temperature gradient between each area. Besides, the new method effectively suppresses the unstable combustion characteristics.