The utility model relates to the technical field of power equipment. The utility model relates to a sleeve, in particular to a converter transformer valve side inflation sleeve. The device comprises asleeve, a four-way valve, a density relay, a connecting pipe, a three-way valve and a pressure gauge, wherein the four-way valve is provided with four interfaces which are communicated with one another; the interfaces are respectively a first interface, a second interface, a third interface and a fourth interface; a first connector of the four-way valve is connected to a pipe body of the sleeve.a second interface of the four-way valve is connected with the density relay; a third interface of the four-way valve is a check valve self-sealing joint; a fourth connector of the four-way valve is connected with one end of the connecting pipe, the three-way valve is provided with a fifth connector, a sixth connector and a seventh connector which are communicated with one another, the fifth connector of the three-way valve is connected with the other end of the connecting pipe, the sixth connector of the three-way valve is communicated with the pressure gauge, and the seventh connector of thethree-way valve is a check valve self-sealing connector. According to the utility model, the maintenance workload is reduced, the equipment maintenance level is improved, and the risk is reduced.