Gear measuring instrument

The utility model relates to the technical field of gear measuring instruments, in particular to a gear measuring instrument which comprises a measuring instrument shell, an inserting groove is formed in the upper end portion of the measuring instrument shell, a top plate is fixedly installed on the side wall of the measuring instrument shell, a vertical strip is fixedly installed at the lower end portion of the top plate, an inner groove is formed in the side wall of the vertical strip, and a U-shaped strip is installed in the inner groove in a sliding mode. Measuring teeth are fixedly installed at the lower end of the U-shaped strip, the fixing mechanism comprises abutting strips, the two abutting strips are slidably arranged in the penetrating grooves, connecting rods are fixedly installed at the opposite ends of the two abutting strips, extrusion plates are fixedly installed at the ends, away from the abutting strips, of the two connecting rods, sliding blocks are fixedly installed on the side walls of th