A fixture for suppressing tool vibration on an outer rim, wherein a pressure claw base, an end face block and a base are installed on the chuck, and the pressure claw is installed on the chuck; a lower pressure plate is fixed on the base, limiting columns and an upper pressure plate are installed on the lower pressure plate, with steel balls and a rubber strip being enclosed in a space formed by the lower pressure plate and the upper pressure plate; and a rubber strip is enclosed in an annular groove formed by a jaw A and a jaw B, and can move radially in the groove. The fixture in the present invention is configured to counteract the vibration of the wheel rim during machining, and thus can effectively eliminate the problem of tool vibration on the outer rim.