Fully automatic automobile piston measurement and intelligent sorting and selection system: This system completes the fully automatic online measurement of the outer diameter, inner diameter, and outer diameter of the piston rod of the automobile piston, manages non-conforming products, and integrates the measurement data for laser QR code marking. Realize the informatization of products. To achieve the best assembly accuracy of automotive pistons and piston rods, the system intelligently sorts the inner diameter of the piston and the outer diameter of the piston rod, achieves intelligent ratio of positive and negative tolerances, and places them in groups. The system adopts the high-precision pneumatic measuring head from Edmond in the United States, with a measurement accuracy of up to 0.002mm. The intelligent sorting system is suitable for the assembly of two or more high-precision parts, which can achieve better fitting accuracy between parts and improve the overall performance of the workpiece.