An efficient and passive micro fuel cell includes an anode plate, a reaction plate, a cathode plate and a condensation plate. The anode plate draws a dilute solution of methanol from a fuel tank to delivery to a series of upper oxidation reaction room through micro-channels by thermal capillarity. The condensation plate separates carbon dioxide and vapor from each other. Meanwhile, the methanol solution is delivered to a plurality of lower oxidation reaction rooms. Protons pass through the inner walls of the reaction holes and a porous membrane layer and arrive in the lower reduction reaction rooms. The lower reduction reaction rooms and the lower oxidation reaction rooms have reaction holes whose inner walls have carbon nanotubes and catalysts. A plurality of upper reduction reaction rooms delivers oxygen for the reduction reaction and drains the reduced water at the same time.