The intelligent assembly system of stepping motor based on Programmable Logical Controller (PLC) and industrial robot is designed. The control system was composed of general control unit, walking unit, engraving and milling unit, assembly unit, conveying unit and warehouse unit, and etc. With adopting Ethernet communication, the data and I/O signal exchange among robot, machine vision, and PLC were realized, and the handling and addition of parts of stepping motor were completed of working and assembling procedures. It improves the level of intelligent manufacturing and assembly, reduces the labor cost, and has high application value.