The invention belongs to the technical field of pre-vulcanizing tire retreading, and relates to a tire retreading vulcanizing device with a single tubeless encapsulating compound cover. Multiple sets of U-shaped arc supporting plates are arranged in a vulcanized tire body along the tire bead opening in a supporting manner, and the supporting plates are coated with an encapsulating compound cover; two conical L-shaped plunger rings which are arranged vertically are arranged in alignment with the ring opening of the tire body; a plurality of force increasing springs are arranged in the U-shaped arc support plates; the conical L-shaped pressing rings are arranged above and below of each U-shaped arc supporting plate respectively, multiple sets of locking noses and buckles are inlaid on the conical L-shaped pressing rings; the cured tire body part is sealed inside the encapsulating compound cover by the U-shaped arc supporting plates and the force increasing springs. The tire retreading vulcanizing device the advantages of reliable structural theory, simple manufacturing process, low tire retreading cost, convenient use and operation, long service life, and good security and stability.