The invention discloses an automobile morphology measurement system mechanical distortion coefficient measuring instrument, and aims at solving the problem that an automobile morphology visual detection system camera lens distortion coefficient cannot be easily and conveniently measured. The automobile morphology measurement system mechanical distortion coefficient measuring instrument is mainly composed of a square frame (1), steel wires (2), sleeves (3) and adjusting screws (4). Stretching of the steel wires is controlled by the adjusting screws (4) so that steel wire images in distortion images are enabled to be changed into original straight lines, and the distortion coefficient is obtained according to the number of rotation turns of the adjusting screws (4). The automobile morphology measurement system mechanical distortion coefficient measuring instrument is simple in structure, high in detection precision, easy and convenient to operate, easy to install, relatively low in cost and reliable in performance.