The invention discloses a pipe bending machine which comprises a shell. The top and the bottom of the left side of the shell are each fixedly connected with a supporting plate. The number of the supporting plates is two. A pipe bending motor is fixedly connected between the two supporting plates. An output shaft of the pipe bending motor penetrates to the top of one supporting plate and is fixedlyconnected with a first rotating rod. The surface of the first rotating rod is fixedly connected with a first pipe bending pulley. A through hole is formed in the top of the shell. An L-shaped plate is movably connected with the left side of the top of the shell. A second rotating rod is fixedly connected with the bottom of one side of the L-shaped plate. According to the pipe bending machine, byarranging the L-shaped plate, the second rotating rod, a movable block, a fixed plate, a rotating block, a fixed rod, a sliding plate, teeth, a transmission motor and a gear, the pipe bending diameterof the machine can be quite conveniently adjusted, lots of manpower and material resources are reduced, adjusting efficiency is improved, and the work efficiency of the pipe bending machine is effectively improved.