The　depth　measurement　according　stereo　vision　is　a　very　popular　method　of　measuring　the　depth　information.　But　the　calculation　in　stereo　matching　is　large,　time-consuming　and　in　large　errors　in　matching,　when　used　in　real-time　systems　to　obtain　depth　information　are　often　ineffective.　This　paper　improves　one　of　the　local　matching　algorithms,　builds　a　complete　real-time　system　for　calculating　depth　image　with　different　SAD　(Sum　of　Absolute　Differences)　matching　window　in　different　texture　regions.　In　this　paper,　we　capture　images　from　the　Bumblebee2　stereoscopic　camera　which　mounted　on　a　small　unmanned　car,　then　use　Matlab　calibrating　the　camera　and　do　the　calculation　to　correct　the　raw　images　and　do　stereo　matching　in　VS2010　to　get　the　depth　map.　This　method　is　simple,　real-time　performance　and　adaptability,　and　the　quality　of　the　depth　map　calculated　from　this　method　is　somewhat　improved.