The invention discloses a portable special measuring tool for the distribution diameter of bolt holes for car wheels, which comprises a fixed caliper angle (1), a movable caliper angle (2) and a dividing rule (3). The fixed caliper angle (1) and the movable caliper angle (2) are connected into an integrated body. The number of various bolt holes and the distribution diameter of corresponding bolt holes are engraved on the dividing rule (3). The movable caliper angle (2) is provided with a scale pointer (4). The scale pointer (4) is arranged in the center of the movable caliper angle. In a measuring process, only the fixed caliper angle (1) and the movable caliper angle (2) need to be placed in two adjacent bolt holes, and the distribution diameter of bolt holes for car wheels can be read according to the number on the dividing rule (3) indicated by the scale pointer (4) on the movable caliper angle (2). The measuring tool has the characteristics of simple operation, low cost and convenient carrying in comparison with the special three coordinate measuring instrument, and is an economical and practical measuring tool for car wheel manufacturers and car after-sale service markets.