The invention provides a transformer with a protective device, and belongs to the field of transformers. The problem that cooling fins on an existing transformer are easy to deform is solved. The transformer with the protective device comprises a transformer tank body and a protective cover, wherein a plurality of cooling fins are fixed on the peripheries of the outer sides of the tank body and the corresponding cooling fins at each side of the tank body are parallel to one another; the protective cover covers the top of the tank body and a plurality of connecting rods are arranged at the bottom of the protective cover; and a cushion block is arranged at the end part of each connecting rod and is provided with two parallel support surfaces, one connecting rod penetrates between two adjacent cooling fins, two support surfaces corresponding to the cushion block are propped against the adjacent cooling fins respectively and the support surfaces are propped against the geometric center positions of the corresponding cooling fins. The protective cover covers the top of the tank body and can protect the tank body; meanwhile, the cooling fins are supported through the support surfaces of the corresponding cushion blocks, so that the stability of the cooling fins can be ensured and the cooling fins can be prevented from deforming and being damaged; and the connecting rods are connected to the bottom of the protective cover, so that overall disassembly or installation of the protective cover can be facilitated.