The invention provides a lead screw clamping type metal hard tube rotary cutter comprising a supporting device, a lead screw device, at least two expanding devices and a cutting device. The supportingdevice is located at the front and back ends of the whole cutter and fixedly connected with the ground. The front and back ends of the lead screw device are erected on the supporting device and can rotate relative to the supporting device. The expanding devices are both arranged on the lead screw device in a sleeving manner and connected with the lead screw device through threads. The expanding devices are sleeved with a to-be-cut metal hard tube. The cutting device is arranged between the two adjacent expanding devices. The supporting device is provided with an early operation motor and a later operation motor. The two motors can control the lead screw and the expanding devices to rotate correspondingly. The cutter is provided with multiple connection rod structures adopting expanding connection rods and front and back rockers to clamp the metal hard tube, a longer contact area is obtained in the length direction of the metal hard tube, and therefore the lead screw clamping type metal hard tube rotary cutter is suitable for to-be-cut metal hard tubes of different lengths, guarantees reliable clamping and avoids deformation.