The utility model relates to an overhead ground wire fault detector and belongs to the electric power system fault detection field. The overhead ground wire fault detector is characterized by comprising a simulation signal input module, a start loop module, an AD conversion module, a data acquisition module, a switching value input module, a time signal input module, a data storing module, a switching value output module, a man-machine interface module, a communication interface module and a central processing unit, wherein the simulation signal input module, the start loop module, the AD conversion module and the data acquisition module are sequentially connected, the data acquisition module, the switching value input module and the time signal input module are connected with the central processing unit, and the central processing unit is respectively connected with the start loop module, the data storing module, the switching value output module, the man-machine interface module and the communication interface module. The overhead ground wire fault detector can rapidly and accurately determine a fault point and guarantees smooth operation of the direct current ice melting work.