The invention relates to a method and device for electrochemical magnetic abrasive finishing machining of an alloy pipe. The device comprises a magnetic abrasive finishing system, an electrochemical reaction system and an ultrasonic vibration system. Permanent magnets and a V-shaped auxiliary magnet are arranged outside and inside an alloy pipe workpiece correspondingly, and magnetic abrasive particles are arranged between the V-shaped auxiliary magnet and the alloy pipe workpiece. An electrolytic bath is sequentially connected with a peristaltic pump and a copper rod electrode, and the copper rod electrode is connected with a carbon brush arranged on the outer side of the alloy pipe workpiece through a direct current power source. An ultrasonic generator is sequentially connected with a transducer, an amplitude-change pole, an elastic collet chuck and a connecting rod through a collecting ring, and the connecting rod is connected with the V-shaped auxiliary magnet. The alloy pipe workpiece is clamped to a three-jaw chuck of a horizontal lathe, and the magnetic abrasive finishing system, the electrochemical reaction system and the ultrasonic vibration system are all installed on a sliding box of the horizontal lathe through a workbench. According to the method and device for electrochemical magnetic abrasive finishing machining of the alloy pipe, by means of the composite process of electrochemical machining and axial ultrasonic vibration assisted magnetic abrasive finishing, finishing machining of the hard alloy pipe is achieved, and the machining efficiency and surface quality are obviously improved.