In actual manufacturing of fine-pitch spur gears， multiple equipment on a single production line usually produce multiple gears with different parameters at the same time. So far， it is not possible to use a single gear measuring instrument to simultaneously and fully inspect these gears with different parameters on the production line in real time. We have developed a gear subpixel edge positioning algorithm based on Facet， a gear center positioning method based on iterative reweighted least squares， a fast positioning method for the intersection of circles and profiles， a sine function fitting tooth number method， and a profile approximate pressure angle measurement method. If combined with appropriate feeding and positioning mechanisms， this method can achieve mixed measurement of multiple different types of gears without the need for clamping， and has high measurement efficiency when unknown parameters are present. It can measure the number of teeth， modulus， pressure angle， tip diameter， root diameter， whole depth of tooth， tooth width， base tangent length， modification coefficient， profile deviation， and geometric error. The experiment result shows that the repeatability accuracy of this method for measuring spur gears with modules ranging from 0.5 to 1.0 mm is 4 μm. This method has important application prospects in the flexible production line of fine-pitch spur gears.