It　is　very　important　to　study　driver　behavior　to　ensure　traffic　safety.　Eight　drivers　were　selected　with　age　between　35　and　48,　Electrocardiograph,　Freecod　data　collecting　system　and　dynamic　GPS　are　utilized　to　study　the　drivers＇　behavior　under　emergency　in　the　Transportation　Communication　Trial　Field.　The　mixing　effects　model　between　maximum　braking　pedal　force　and　heart　rate　change　rate　were　established,　then　the　factors　such　as　driving　time,　personality,　driving　experience　and　age　are　considered　by　the　driving　pones　factor　K,　finally　the　improved　mixing　effects　model　based　on　driving　pones　factor　K　was　given.　©　2012　American　Scientific　Publishers　All　rights　reserved.