The invention discloses a cutting machine used for diesel engine water pipes. The cutting machine comprises a bottom plate. A drive device and a first supporting plate are fixedly connected with the upper surface of the bottom plate. The first supporting plate is located on one side of the drive device. The front face of the drive device is fixedly connected with a first rotating shaft. The surface of the first rotating shaft is sleeved with a first bearing. The surface of the first bearing is fixedly connected with the front face of a second rotating shaft through a first connection rod. The surface of the second rotating shaft is sleeved with a second bearing. According to the cutting machine used for the diesel engine water pipes, by arranging the drive device, a third rotating shaft and a third bearing, a rotating shaft of a first motor can drive a disc to rotate, and therefore the bottom end of a second connection rod can swing leftwards and rightwards back and forth, the top end of a third connection rod can swing leftwards and rightwards, a cutting device can circularly and repeatedly cut the water pipes placed on two clamping devices, the cutting machine can unceasingly work, the work efficiency of the cutting machine is improved, and meanwhile the production efficiency of the water pipes used for diesel engines is also improved.