Provided are a fabricated building combined tool type outer protection frame system and a construction method thereof. The fabricated building combined tool type outer protection frame system is formed by splicing a plurality of single-truss protection frames through bolts, and each single-truss protection frame comprises a pedal, a rectangular structural frame for fixing the pedal, a half-pozidriv structure protection screen and a triangular supporting frame for supporting the rectangular structural frame. The triangular supporting frames are directly fixed to a structural wall or fixed to the structural wall through modular extension supporting frames. Connecting lug plates for being fixed to the rectangular structural frames are arranged on horizonal supporting rods of the triangular supporting frames, and strip-shaped through holes are formed in the connecting lug plates. Vertical square steel tubes are arranged on the side walls, away from the structural wall, of the rectangular structural frames, inserting rods for being fixed to the vertical square steel tubes in an inserted manner are arranged on the bottom faces of the half-pozidriv structure protection screens, and the inserting rods are fixed through bolts after being inserted into the vertical square steel tubes. The fabricated building combined tool type outer protection frame system is easy to operate during fabricated building construction, construction time is saved on the premise of guaranteeing safety, and the progress of building construction engineering is promoted.