The invention discloses a full automatic pipe cutting machine. The pipe cutting machine comprises a feeding drive part, a cutting drive part, a pipe clamping part, a cutting part, an unloading part and a cutting measurement part which are sequentially arranged on an operating platform, wherein the feeding drive part conveys pipes to the cutting part by a driving wheel and a rolling wheel, then the pipes are cut off by a cutting tool driven by the cutting drive part; the driving wheel of the pipe cutting machine is driven by a stepping motor, and the lengths of the cut pipes can be accurately detected and controlled according to the electrical signals of stepping quantity of the stepping motor and the data of radius of the driving wheel; and in addition, the operating platform is also provided with an infrared distance measurement sensor, and the length accuracy of the cut pipe is jointly ensured by the electrical distance measurement signals and the movement detection signals of the stepping motor. By adopting the clamping feeding structure, the automatic cutting structure, the automatic clamping structure, the automatic unloading structure and the automatic cut pipe-length measurement and control mechanism, the degree of automation of the pipe cutting machine is improved.