The invention provides a multi-size automatic steel pipe cutting machine. The multi-size automatic steel pipe cutting machine comprises a bottom plate, an upper plate, a conveying support, a first unthreaded shaft, a lead screw sliding table, a lead screw, a storage bin, a second unthreaded shaft, a pipe blocking support, a first feeding support, a second feeding support, a swing cutting unit, a feeding unit, a third servo motor, a first feeding supporting plate, a second conveying belt, a second feeding supporting plate, a feeding unit, a grabbing unit and the like; the grabbing unit is usedfor rapidly and accurately taking and feeding, the feeding units are uniformly distributed on the circumference of the steel pipe to accurately position the steel pipe, and the swing cutting unit cancontinuously and efficiently cut the steel pipe. The multi-size automatic steel pipe cutting machine greatly improves the machining efficiency of material machining, and liberates the labor force.