The invention discloses a ladle furnace (LF) refining steel ladle sealing device and a use method thereof. The LF refining steel ladle sealing device comprises a ladle body and a ladle cover. The bottom edge of the ladle cover and the top edge of the ladle body are sealed and buckled. The ladle cover is provided with one or more wire feeding pipes. When the ladle cover and the ladle body are buckled, the bottoms of the wire feeding pipes are located above molten steel inside the ladle body. When the LF refining steel ladle sealing device is used, the ladle cover is sealed on the ladle body through hoisting equipment, alloy core wires penetrate through the wire feeding pipes, and the wire feeding depth is controlled to be 100-200 mm below the interface of the molten steel. The ladle body is sealed through the ladle cover, so that contact burning of strong deoxidizer and oxygen in air on the steel slag interface is avoided, and loss of the strong deoxidizer is reduced. Contact burning of the alloy core wires and the oxygen is reduced, and the situation that calcium compounds in the molten steel cannot be drained and pollutes the molten steel is avoided. Secondary oxidization of the molten steel in the wire feeding process is avoided, dust emission is reduced, and the environment is protected.