Abstract:  Carbon deposition caused by reforming in micro-combustor brings catalyst deactivation and channel snarl-up. The technology of methane wet-air autothermal reforming is presented to realize methane last, steady-state combustion and to reduce carbon deposition. The effects for carbon deposition below 973K are discussed by thermodynamic analysis at 0.1MPa in this paper. Results show that temperature, air-methane ratio and steam-methane ratio contribute a lot to the carbon deposition. In micro-combustor, carbon deposition increases with temperature increasing first, then decreases; it is beneficial to reduce carbon deposition as well as to produce hydrogen with air and steam increase under lean oxygen; at the same time, autothermal reforming compared with non-steam system is superior on reducing carbon deposition in micro-combustor. When methane mass flow is 6.6g/h, air-methane ratio and steam-methane ratio are respectively 2 and 1 in micro-combustor, the carbon deposition temperature range is at 680K~850K. The largest mass fraction of carbon deposition is 0.66% and occurred at 785K, also the methane conversion rate and the mass fraction of hydrogen are approximately 53.43% and 2.37%; and that, requirements of air-methane ratio and steam-methane ratio to eliminate the carbon deposition are about 2.4 and 1.1 respectively.