The invention relates to a metal hard pipe rotary cutting machine. The metal hard pipe rotary cutting machine comprises a delivering device, a conveying device, a cutting device, a collecting device and two clamping devices; a to-be-cut metal hard pipe which comes from a former working procedure is contained in the delivering device; the distance between the front end surface of the delivering device and the rear end surfaces of the clamping devices is not larger than twice the diameter of the to-be-cut metal hard pipe; the two clamping devices are arranged back to back; the clamping devices and the cutting device are located at the same rotation center; the cutting device is located on the front ends of the two clamping devices; and the collecting device is located on the front end of thecutting device. The clamping devices can perform clamping synchronously on a circle from multiple directions, and besides, the radian of clamping plates are consistent with the curvature of the metalhard pipe, so that the metal pipe is not damaged during the clamping process, and deformation of clamped parts is not caused; and by adopting the cutting machine, the problems of low metal hard pipecutting quality, low cutting efficiency and needs for secondary trimming machining are solved, and the cutting machine is especially applicable to cutting machining of thin-wall long pipes.