The invention discloses a rapidly-started self-heating type micro-reactor for producing hydrogen by reforming methanol. The micro-reactor is formed by sequentially assembling a cover plate assembly, a reforming hydrogen production plate, a first methanol combustion plate, a methanol combustion porous plate and a second methanol combustion plate in a sealing manner from top to bottom, wherein a methanol reforming cavity is formed in the reforming hydrogen production plate, the reforming hydrogen production plate is loaded with a reforming catalyst and is used for producing hydrogen by reforming methanol; the first methanol combustion plate has a methanol catalytic combustion cavity loaded with a combustion catalyst to supply heat through the combustion of methanol; and the methanol is combusted to supply energy for producing hydrogen by reforming methanol, so as to realize the self-heating operation of the micro-reactor. According to the micro-reactor, combustion fuels including methanol and air are independently supplied, so that the air inflow of a combustion chamber and the use efficiency of the catalyst are improved, and the starting time of the micro-reactor is shortened. The micro-reactor is short in starting time, compact in structure, high in energy density and hydrogen production efficiency, low in manufacturing cost and easy in assembling of an integral structure and can be applied to occasions for producing hydrogen by reforming middle and small flow of methanol so as to directly supply hydrogen to hydrogen fuel cells.