Detecting　vehicle　in　video　is　a　challenging　problem　owing　to　the　motion　of　vehicle,　camera　and　background,　and　to　variations　of　speed.　This　paper　proposes　a　classifier-based　supervised　method　to　detect　moving　vehicle　from　a　moving　camera.　Motion　descriptors　based　on　oriented　histograms　of　differential　optical　flow　be　able　to　describe　the　motion　pattern　of　the　object　from　changing　background.　And　Extreme　Learning　Machine　provides　excellent　generalization　performance　at　fast　speed.　Our　sample　images　taken　by　a　camera　in　helicopter　include　2000　images.　Experiment　results　shown　that　this　proposed　method　has　not　only　overall　discrimination　performance　but　also　low　computational　cost.