The invention provides a DC voltage divider fault monitoring device. The DC voltage divider comprises an insulated casing and a high-voltage arm and a low-voltage arm in serial connection and mounted in the insulated casing, wherein the top end of the insulated casing is connected with a high-voltage lead, and the bottom end is grounded. The fault monitoring device comprises a first current sensor, a second current sensor, a secondary voltage dividing module, a data acquisition module and a data processing and merging module, wherein the secondary voltage dividing module, the data acquisition module and the data processing and merging module are sequentially connected; the other end of the secondary voltage dividing module is connected with the low-voltage arm, and the connection part is grounded through a low-voltage lead; the first current sensor is arranged at the bottom part of the insulated casing, and the output end is connected with the data acquisition module; and the second current sensor is arranged on the low-voltage lead, and the output end is connected with the data acquisition module. The technical scheme provided by the invention is high in reliability and wide in application range, the working state of the DC voltage divider can be monitored in real time, and reference is provided for accurately processing the operation fault of the DC voltage divider.