Good pantograph net relationship is one of the important factors for the normal run of electrified railway. Using machine vision technology to measure the thickness of pantograph slide can reduce the pantograph net accidents caused by human error. The pantograph slide pictures taken in the laboratory environment were processed by image grayscale processing, perspective correction, pantograph slide image filtering and pantograph slide image enhancement. This paper proposes a method of image tracking after edge detection and morphology open and close operation on pantograph slide image, realize the pantograph slide edge detection and positioning, The minimum value of pantograph slide thickness is calculated. Carry out measurement experiment to the pantograph slide, and the results obtained by this method were compared with the measured values, and the measure error was basically ±0.5mm. The results show that the image processing method proposed in this paper can realize the pantograph slide abrasion detection and has great value to the practical application research.