The invention discloses a vehicle-mounted USB self-purification ashtray. The vehicle-mounted USB self-purification ashtray comprises an inner cylinder and an outer cylinder. The outer cylinder sleevesthe inner cylinder in a sliding mode, and an end cover is hinged to one side of the top end of the outer cylinder through a rotating shaft; openings are formed in the upper end and the lower end of the inner cylinder respectively, the opening in the lower end of the inner cylinder is arranged to be of a boss structure, a thread-rotary-connection closed bottom cover is arranged at a small openingof the boss structure, the lower opening of the inner cylinder is closed through the closed bottom cover, a sealing ring is arranged at the matched connection position of the closed bottom cover and the inner cylinder, a sponge block is arranged in the boss structure of the inner cylinder, and a grid plate is arranged above the sponge block and in sliding fit with the inner side wall of the innercylinder. The vehicle-mounted USB self-purification ashtray is small in size, can achieve the effects of purifying smoke and rapidly extinguishing cigarette ends while having the effects of a traditional ashtray, and is quite suitable for being used in an automobile.