The invention provides a full automatic cutting device for modified polypropylene (MPP) cable protection pipes. The full automatic cutting device comprises a supporting mechanism and a cutting mechanism, wherein the supporting mechanism is used for supporting the cable protection pipes and the cutting mechanism is used for cutting the cable protection pipes. The supporting mechanism comprises a base, a first support and a second support. A first supporting unit and a second supporting unit are arranged on the opposite faces of the first support and the second support respectively. The first supporting unit comprises a first supporting assembly and a second supporting assembly, and the second supporting unit comprises a third supporting assembly and a fourth supporting assembly. The cutting mechanism comprises a mounting seat, a third support, a fourth support, a first cutting unit and a second cutting unit. The second cutting unit is located above the first cutting unit. The first cutting unit corresponds to the first supporting assembly and the third supporting assembly. The second cutting unit corresponds to the second supporting assembly and the fourth supporting assembly. The full automatic cutting device can be used for cutting the cable protection pipes of different diameters at the same time, the cutting speed is high, cutting is accurate, the quality of obtained products is good, and the working efficiency is high.