The utility model discloses an electrical test instrument dehumidifying device comprising a drying box body which comprises a drying cavity and an equipment installation cavity. An electric heater located on the cavity wall and supporting plate clamping bases located on the left side cavity wall and the right side cavity wall are arranged in the drying cavity, and clamping grooves used for detachably installing supporting plates are formed in the supporting plate clamping bases at intervals in the longitudinal direction. The equipment installation cavity is provided with a draught fan used forconveying air outside the drying box body into the drying cavity, an air return opening communicated with the drying cavity, and a ventilation and drainage opening used for exhausting the air insidethe equipment installation cavity to the outside. According to the electrical test instrument dehumidifying device provided by the utility model, the electrical test instrument can be dried and dehumidified through flowing hot air, and wet moisture and suspended dust particles of the electrical test instrument are removed.