The invention relates to a steel pipe cutting machine. The steel pipe cutting machine comprises a rack, a first motor, a rotating drum, friction assemblies, an installing drum rotatably arranged in the rotating drum in a matched mode, sleeves, a rotating pipe, a first air bag arranged in the rotating pipe, an air supplying mechanism used for supplying air to the first air bag, a second motor slidably installed in the installing drum and a cutting disc which is in transmission connection with an output shaft of the second motor; an output shaft of the first motor, the rotating drum and the installing drum are coaxially arranged; the sleeves and the installing drum are arranged in parallel; the first air bag is shaped like a cylinder and provided with a channel used for allowing a steel pipeto penetrate; and sleeves are connected to the rack. According to the steel pipe cutting machine, rotating fit between the rotating pipe and the sleeves is skillfully utilized, rotation of the friction assemblies (particularly, friction layers) on the steel pipe is combined, therefore, the steel pipe needing to be cut can rotate, the steel pipe is cut in the rotating process, uniform cutting canbe conducted, the cutting quality is improved, and meanwhile the cutting disc can be better protected.