The invention discloses a combined cutting tool for cutting a circular groove on an end surface and a blade mounting frame of the combined cutting tool. The combined cutting tool comprises the blade mounting frame and a tile-shaped blade which has a rear end fixed on the blade mounting frame in a detachable mode and is provided with an inward concave surface and an outward convex surface, wherein the blade mounting frame comprises a cutter bar which is extended along the front-and-back direction; a supporting structure which is fixedly connected with the blade through a fixing mechanism is arranged at the front end of the cutter bar; an arc-shaped supporting surface which is matched with the outward convex surface of the blade in a coincided mode is arranged on the supporting structure; the fixing mechanism comprises a screw pin for limiting the blade and a pressing block which is pressed on the inward concave surface of the blade; and the pressing block is provided with a pressing surface which is matched with the inward concave surface of the blade in a pressing mode. The blade is used as a cutting part of the whole combined cutting tool, and the blade mounting frame is used as a carrier of the whole combined cutting tool; and the blade and the blade mounting frame are separated from each other, and the blade is only required to be detached from the blade mounting frame when replaced, so that waste is prevented.