Abstract: Vision positioning system is the key technology for improving the accuracy of high precision mounter.The machine vision was proposed to detect the deviation of surface mounted technology(SMT)components and PCB board.The regional growth method and the maximum internal rectangle method were used to calculate the displacement and angle center of the SMT components and PCB board, respectively, and the displacement and angle that needed correction were obtained.Experiments show that the detection accuracy of the component center can reach 30 μm and the total processing time is 63.6 ms, so it can meet the requirements for fast detection of mounting components with high precision.