The　reaction　time　of　driver　is　the　important　matter　of　car　following　model　research.　The　high　precision　GPS　in　vehicle　was　used　to　collect　car　following　data　in　this　paper.　And　the　time　serial　car　following　data　that　reflecting　driver　behavior　and　vehicle　moving　character　in　real　traffic　flow　was　collected.　The　analysis　method　of　driver　reaction　time　in　following　vehicle　was　built　especially　aiming　at　deceleration　regime.　The　probability　distributing　function　and　parameters　of　driver　reaction　time　in　following　vehicle　at　deceleration　regime　were　built,　the　function　of　relationship　between　driver　reaction　time　and　car　following　speed,　and　the　function　of　relationship　between　driver　reaction　time　and　headway　were　built　in　this　paper.