The invention provides a fracture-preventing pre-alarming device and method used for a winding wire rope of a rotary drilling rig. The device comprises a pre-alarm device, a microcomputer and a sensor, all of which are orderly connected. The microcomputer is connected with a laser spray gun. A gun opening of the laser spray gun faces towards the winding wire rope and the distance between the gun opening and the winding wire rope is adjustable. The sensor is installed on the winding wire rope. The fracture-preventing pre-alarming method used for the winding wire rope of the rotary drilling rig has the following steps of monitoring whether leakage flux during operation is caused by the winding wire rope of the rotary drilling rig or not in a real-time manner; determining whether an analog voltage signal exceeds the pre-alarming value or not; labeling a wire-fracturing position of the winding wire rope and controlling the rotary drilling rig to stop working; and repairing the wire-fracturing position of the winding wire rope. The fracture-preventing pre-alarming device and method used for the winding wire rope of the rotary drilling rig have the following beneficial effects: the wire rope can be detected in a real-time manner and an alarm can be raised in a real-time manner; problems can be timely dealt with once being found, thereby avoiding dangers; the dangerous region for wire fracture of the wire rope can be labeled so as to help workers find fractured wires and eliminate fault in time, thereby ensuring that the construction of ultra high voltage transmission lines can be carried out smoothly.