With　the　development　of　Internet　of　Thing,　the　demand　for　clock　synchronization　in　IoT　application　is　continues　increasing.　However,　due　to　the　heterogeneous　devices　and　interfaces　in　IoT　access　system,　most　of　the　traditional　methods　for　clock　synchronization　are　not　applicable.　In　this　paper,　we　present　novel　clock　synchronization　architecture　for　IoT　access　system　in　the　practical　application　scenario.　By　adopting　the　RTC,　GPS,　NTP/SNTP　and　PTP　technologies,　the　architecture　can　be　implemented　with　different　strategy　to　meet　the　different　needs　of　clock　synchronization　precision.　A　typical　vehicle　monitoring　system　based　on　the　proposed　architecture　for　real-time　video　monitoring　and　environmental　information　acquisition　has　been　designed　and　implemented.　The　experimental　results　indicate　the　system　can　synchronize　the　clock　with　high　precision　and　reliability.　©　2016　IEEE.