Drivers　are　used　to　steering　when　they　meet　obstacles　in　order　to　protecting　the　measure　and　lives.　Freecod-data　collector,　dynamics　GPS　and　the　sensors　of　steering　degree　was　utilized　to　study　the　rule　of　driver　steering　velocities,　the　relationships　between　maximum　steering　velocities　and　distance,　and　as　well　as　maximum　steering　velocities　and　driving　velocities　were　eastablished.　The　results　show　that　drivers　steering　operation　includes　five　periods　and　also　indicates　that　driver　maximum　steering　velocities　is　changing　with　distance　in　nagitive　and　driver　maximum　steering　velocities　is　changing　with　distance　in　positive-linear.　The　regressive　formulas　were　also　given.　This　research　help　us　to　comprehend　driver　behavior　under　emergency.