The utility model provides a protective housing of a transformer station terminal box. The protective housing covers the transformer station terminal box located on a mounting base. The protective housing of the transformer station terminal box comprises a tope cover, side plates and case doors; the top face of the top cover comprises an inclined plane, and the bottom face of the top cover is provided with first mounting holes; the side plates comprises a first side plate and a second side plate which are oppositely disposed, one end of each of the first and second side plates is provided with a folding edge for being connected with the top cover, the other ends of the first and second side plates are connected with the mounting base and provided with a sealing layer, the folding edges are provided with second mounting holes corresponding to the first mounting holes, and bolts pass through the second mounting holes; and the case doors comprise a first case door disposed corresponding to an opening of the transformer station terminal box and a second case door disposed in a manner that the first case door and the second case door are oppositely disposed, and the first case door is provided with a perspective part. The protective housing of the transformer station terminal box can safely protect internal equipment in of the terminal box without power-off replacement of the terminal box.