An auxiliary cutting device provided with a cutting gauge comprises a round ring, locating magnets, locating bolts and the cutting gauge, wherein the locating magnets are mounted at two ends of the round ring, the locating bolts are arranged at the two ends of the round ring and can adjust the level, the cutting gauge is arranged at the upper part of the round ring, and the cutting gauge is in a cross structure formed by connecting a vertical bar and a horizontal bar; a sleeve which is used for placing a cutting gun is mounted on one side of the horizontal bar, and a roller is mounted at the end part of the horizontal bar. According to the auxiliary cutting device provided with the cutting gauge, the structure is simple, the use is convenient, balance and stability of pipeline cutting can be guaranteed, and the concentricity and the accuracy of pipeline holes are improved greatly; besides, the device is convenient to carry and can be applied to pipeline hole cutting of pipes with different diameters, and time and labor are saved; the production cost is reduced greatly, and the production efficiency is improved.