Vegetation encroachment and its monitoring near high voltage power line is a challenging problem for electricity distribution companies. Electric supply companies monitor the vegetation/trees near power lines to avoid the blackouts that may occur in case of an improper monitoring of vegetation. The uninterrupted electric power supply is vital for industries, businesses, and daily life. Many approaches are employed to monitor vegetation/trees near the transmission line poles, but these approaches are more time consuming and expensive. In this paper, we have proposed a novel approach to monitor the vegetation near or under the power poles using satellite stereo images which were acquired using QuickBird and IKONOS satellite images and calculated disparity map using stereo matching algorithms i.e. dynamic programming (DP) and Hierarchical dynamic programming (HDP). The 3D depth of vegetation is based on disparity map which has been measured using stereo algorithms. Results showed that HDP performs well as compared to DP based on QuickBird and IKONOS satellite stereo images in terms of accuracy.