The invention relates to an automatic high-speed metal tube cutting machine. The automatic high-speed metal tube cutting machine comprises a machine frame assembly and a shearing machine assembly. A lower hydraulic cylinder assembly is arranged at the bottom of the shearing machine assembly. A side hydraulic cylinder assembly is arranged on a side face of the shearing machine assembly. The shearing machine assembly comprises a main machine base, wherein an inner floating cutter assembly, an inner fixed cutter assembly, an outer floating cutter assembly and an outer fixing cutter assembly are arranged in the main machine base. The outer floating cutter assembly is sleeved with an upward-downward moving die and a leftward-rightward moving die, wherein the leftward-rightward moving die and the upward-downward moving die are tightly buckled, the lower surface of the upward-downward moving die is fixedly connected with a first piston rod of the lower hydraulic cylinder assembly, and a side face of the leftward-rightward moving die is fixedly connected with a second piston rod of the side hydraulic cylinder assembly. The automatic high-speed metal tube cutting machine has the advantages that no scrap iron exists, one time of cutting is completed within three seconds, noise is low, shearing accuracy is high, automatic cutting can be achieved, the automatic high-speed metal tube cutting machine is suitable for shearing workpieces with the fixed size and any lengths in batches, use is safe, man-machine work efficiency is high, the structure is firm, rigidity is high, vibration is small, the cutting size can be converted at a high speed, and operation and maintenance are easy and convenient.