The invention discloses a portable inner cavity micro-hole drilling machining device. The device comprises a fixing base, a feeding mechanism, a lifting mechanism, a cutter transmission mechanism anda detachable cutter structure; the fixing base is horizontally arranged; the feeding mechanism comprises a first motor, a ball screw and nut pair, a nut seat, a bearing block and a flange plate; the lifting mechanism comprises a sliding table base, a sliding table, a lifting transmission shaft, a gear, a rack, an adjusting handle and a locking assembly; a dovetail groove is formed in the front endsurface of a sliding groove part in the upward direction; a dovetail table is arranged on the rear end surface of the sliding table and is arranged in the dovetail groove; the cutter transmission mechanism comprises a connecting rod, a second motor, a driving pulley, a belt, a driven pulley and a main shaft; the driving pulley is in transmission connection with an output shaft of the second motor; the driven pulley is in transmission connection with the main shaft; and the detachable cutter structure is arranged on a cutter mounting section of the main shaft. The device has the advantages ofbeing capable of solving the problems of the machining difficulty and the machining cost effectively, high in machining precision, convenient to operate, small in size, easy to carry and the like.