The invention provides a cooling system for a transformer. The cooling system comprises a box body; a transition cavity is arranged at the bottom of the box body; a transformer cavity is arranged above the transition cavity and is internally provided with an auxiliary box; the auxiliary box is internally provided with a transformer main body and is provided with air outlet holes; the auxiliary boxis internally provided with an air guide pipe; the air guide pipe is provided with an induced draft pipe; a first induced draft box body is arranged at the outer side of the transformer main body andis provided with a first through hole and a second through hole; a second induced draft box body and a water diversion cavity are arranged at the outer side of the first induced draft box body; the bottom of the water diversion cavity is connected with the transition cavity by means of a drain pipe; the second induced draft box body is provided with an air guide hole, and the air guide hole is connected with an air inlet hole of an exhaust pump; the bottom of the air guide pipe passes through the transition cavity and is connected with a cooling box; the cooling box is connected with a filtering box. The cooling system for the transformer has the advantages of being reasonable in structure, not affecting the normal work of the transformer when being used for cooling, and improving the environmental protection performance and the efficient utilization rate of resources.