The utility model discloses an outdoor terminal box of a transformer substation, which comprises a base and a box body arranged on the base, the box body comprises an equipment bin, a heat dissipationbin and a drying bin, a bin door is arranged at the position of the equipment bin on the box body, the heat dissipation bin is positioned above the equipment bin, and a heat dissipation device is arranged in the heat dissipation bin; the drying bin is located below the equipment bin, and a plurality of activated carbon adsorption plates are arranged on the two sides of the mounting box in the drying bin correspondingly. A heat dissipation bin, an equipment bin and a drying bin are arranged in the outdoor terminal box. A fan is arranged in the heat dissipation bin to provide flowing airflow for the equipment bin; according to the terminal box, heat dissipation and cooling treatment is carried out in the equipment bin, the temperature in the box body is reduced, and the activated carbon adsorption plate is arranged in the drying bin to carry out drying and dehumidification treatment on air entering the box body, so that external moisture is prevented from entering the box body, and thephenomena of moisture, condensation and the like in the terminal box are effectively prevented.