Abstract: Aiming at the problems of low efficiency, accuracy, and poor reproducibility of manual measurement of weight quality, the workflow of weight measurement, stability of mass comparator, motion control of three-dimensional manipulator, and positioning accuracy of loading and unloading were studied. The basic principle of the Programmable Logic Controller (PLC) servo control system was analyzed, and a set of PLC-based control system for weight automatic verification devices was designed and developed. Taking CX programmer as the development platform, the control system was established by using PLC and ladder diagram programming language, which realized the automatic control of the whole process of weight loading and unloading and the automatic detection of weight quality. The overall debugging and experimental verification of the system were also carried out. The results showed that the control system has the advantages of simple structure, high efficiency, and avoiding human error, and improves the automation level and reliability of weight verification.