Most of the oil and gas fields in China are located in remote areas with low ambient temperature throughout the year. It is necessary to heat the wellhead to prevent freezing. Micro catalytic burners can be used in many heating scenarios. However，methane alone is difficult to stably catalytically self-ignite at room temperature. By using China's abundant renewable energy such as wind power and photovoltaic power to produce green hydrogen and mix it with methane on precious metal Pt，catalytic self-ignition at room temperature can be achieved. Research on catalytic combustion of green hydrogen and methane mixed fuel is expected to play an important role in developing new techniques for wellhead anti-freezing and accelerate "low-carbonization" of energy. The reaction files of the catalytic reaction mechanism of hydrogen and methane mixed fuel on the surface of Pt catalyst are studied and imported into Fluent 2021R1 to build a three dimensional numerical computation model for the catalytic combustion of hydrogen and methane mixed fuel in micro-channels and explore the effects of the mixing ratio of hydrogen-methane and the synchronous and asynchronous supply of hydrogen and methane on the ignition of catalytic combustion. It is found that a low proportion of hydrogen leads to the deactivation of the catalyst，and a high proportion of hydrogen can trigger catalytic spontaneous combustion at room temperature. The synchronous supply mode is associated with a higher upper limit of the hydrogen proportion for catalyst deactivation and a smaller lower limit of the hydrogen proportion for catalytic spontaneous combustion. The simulation results show that the synchronous supply of hydrogen and methane，an inlet velocity of 1.0 m/s，a hydrogen and methane concentration ratio of 1∶1，and a micro-channel diameter of 1.5 mm are favorable for the catalytic self-ignition of hydrogen and methane mixed fuel. The performed numerical simulation reveals the catalytic self-ignition characteristics of green hydrogen and methane mixed fuel at room temperature and the evolution law of the ignition process，which lays a foundation for the application of such heating processes in oil and gas field production.