A device for cleaning the surface of a molybdenum wire at high temperature, comprises a wire pay-off mechanism, a first wire guiding wheel, a cleaning mechanism, a second wire guiding wheel, and a wire take-up mechanism; wherein the two ends of a furnace body of the cleaning mechanism are provided with an inlet hole and an outlet hole for the molybdenum wire. Electrodes connected to a power supply are provided at the inlet hole and in a central part inside the furnace body. An upper part of the furnace body is provided with a gas outlet and a lower part thereof is provided with a wet hydrogen inlet; a heating section is formed between the electrode located at the inlet hole and the electrode located in the central part, and a cooling section is formed between the electrode located in the central part and the outlet hole.