Quantity　criterion　and　compartmentalizing　measure　of　car　following　regime　were　not　put　forward　because　of　lacking　time　serial　car　following　data.　After　reviewing　the　research　of　car　following　models,　the　various　compartmentalizing　car　following　regimes　and　key　parameters　for　the　same　model　were　deducted　in　this　paper,　then　the　unite　car　following　model　that　reflects　driver　behavior　and　vehicle　run　characteristic　in　fact　traffic　flow　is　established.　196000　pairs　of　car　following　data　of　fact　traffic　flow　in　Beijing　expressway　were　collected,　and　208　time　segments　data　were　selected,　that　include　only　one　regime　car　following　data　in　every　time　segment.　Dynamic　gathering　measure　of　average　acceleration　of　time　segment　car　following　data　was　taken　to　compartmentalize　full　car　following　process　to　three　regimes,　such　as　acceleration　regime,　stabilization　regime　and　deceleration　regime.