A inspection method of lost beads bearing based on robot vision was proposed. First, bearing image was captured by smart camera. Then, the optimal threshold of bearing image binarization was gained by using Otsu algorithm. The binarization processing result of the bearing image was used to extract the characteristics of the bearing beads. Last, the communication of PLC and smart camera was established, the lost beads bearing was sorted out by PLC. Experimental results show that the robot vision inspection system has high work efficiency and high reliability.