The invention discloses a detection method and device for the fault of direct current ice thawing overhead ground wires, relates to the fault processing technology in the ice thawing process of a power transmission line and belongs to the field of fault monitoring of a power system. A high-voltage signal generator (1) connected with overhead ground wires M and N and a detector are arranged at a measuring point of a substation, the method comprises the steps of firstly injecting a high-voltage pulse signal between the overhead ground wires M and N and the ground by the high-voltage signal generator (1), then measuring the injection moment of the high-voltage pulse signal and the reaching moment of reflected waves of the high-voltage pulse signal at a fault point F of the overhead ground wires M and N by the detector, calculating the distance between the fault point F and the measuring point by using a single-end traveling wave fault ranging technology, thus determining the position of the fault point F. The detection method and device for the fault of the direct current ice thawing overhead ground wires solve the fault monitoring problem in the direct ice thawing process of the power transmission line, so the precision for positioning the fault point is improved, and the method and the device have the advantages of simple operation, precise positioning and the like.