Abstract: A single-point clamp of four-wheel aligner for vehicles connected to a fixing hub nut on the wheel comprises a sleeve, a single-point variable hexagonal grip, a fastening nut, a connecting board, and a target board with magnets. The single-point variable hexagonal grip and the fastening nut are respectively disposed at two ends of the sleeve. The single-point variable hexagonal grip is firmly lodged in the fixing hub nut. Two ends of the connecting board are respectively connected to the sleeve and the target board. A using method includes steps of: (1) loosening the fastening nut of the single-point clamp; (2) inserting the single-point variable hexagonal grip into the fixing hub nut of the wheel; and (3) rotationally fastening the fastening nut for clamping the fixing hub nut firmly. The single-point clamp and the using method thereof obtain a simple structure, an easy installation, low costs, and a resource-saving effect.