The invention discloses a shock-proof structure of a transformer. The shock-proof structure comprises an external buffering mechanism and an internal buffering mechanism, wherein the external buffering mechanism consists of a first tightening screw rod and the like; the first tightening screw rod is screwed into a matching threaded hole in a guide body; the tail end of the first tightening screw rod is pressed against a first baffle plate; the right side of a first energy storage body is provided with a first piston rod which is directly connected with the outside of a transformer shell; the bottom of the guide body is directly welded together with a bottom plate of a transport trailer; the internal buffering mechanism consists of a cover and the like; a double-helix guide body of the internal buffering mechanism is welded on a tank wall of a transformer oil tank in a scraf welding way; a second tightening screw rod is screwed into a matching threaded hole in the double-helix guide body; the screw rod side of the double-helix guide body extends out of the oil tank; the tail end of the second tightening screw rod is pressed against a second baffle plate; the right side of a second energy storage body is provided with a second piston rod which is connected with an insulator for supporting a transformer iron core. By adopting the shock-proof structure, the impact resistant and vibrating resistant performance of the transformer during transportation can be enhanced in a mobile substation project.