Abstract: In this paper,the vision subsystem of a cleaning robot working under high voltage conditions is presented. Utilizing both general and detail image information,various difficulties resulting from online high voltage cleaning and complicated outdoor background are successfully overcome,and a new hybrid method is designed,which has the advantages of iterative threshold,projection transform,Hough Transform and other algorithms. With the above method,the speed and reliability of the system is greatly improved and automatic insulator positioning and manipulator servoing is achieved.