Cutting knife for conventionally cutting underground plastic pipeline on non-excavation drilling machine

The invention belongs to the technical field of non-excavation pipe-laying machinery, and particularly relates to a cutting knife for conventionally cutting an underground plastic pipeline on a non-excavation drilling machine. The cutting knife comprises a center shaft, wherein a central through hole is formed in the gyration center of the center shaft; a male thread is arranged at one end of the center shaft, and a female thread is arranged at the other end of the center shaft; the female thread and the male thread are respectively arranged coaxial to the central through hole; three cutting blades are uniformly distributed and arranged on the circumferential surface of the center shaft; a cutting angle a of 15-20 degrees is formed between a cutting edge of each cutting blade and the axis of the center shaft. The provided cutting knife for conventionally cutting the underground plastic pipeline on the non-excavation drilling machine is simple, ingenious and reasonable in structure, and cutting operation can be conveniently and quickly carried out on underground pipes needing to be changed by using the cutting knife.