In　order　to　protect　drivers＇　safety　under　emergency,　utilizing　the　driver＇s　behavior　and　reaction　research　platform　and　cluster　technology,　a　structure　model　between　physiological　reactions　and　the　braking　parameters,　which　include　braking　reaction　time　and　maximum　braking　pedal　power,　was　established.　The　traits　of　the　driver＇s　physiological　reactions　were　discussed;　the　relationship　was　studied　and　analyzed.　Then　using　the　fuzzy　adaptive　network,　the　braking　behavior　was　predicted　based　on　the　physiological　data.　The　results　show　the　fact　that　the　physiological　indices　of　the　driver　change　in　different　emergency　situations　are　obvious.　The　more　driving　experience　the　driver　has,　the　little　the　physiological　indices　change.　The　prediction　errors　of　the　FAN　were　under　2%.