Abstract: Instantaneous traffic information can be collected by the Floating Car Data(FCD) method.Based on the establishment of "Shenzhen Urban Transportation Simulation System"(SUTSS),the paper explored how to use taxis as the data collection sensors in Shenzhen.Due to the nature of FCD,continuous GPS data such as routing velocities and coordinates can be collected by any GPS equipped vehicle.Therefore,relevant algorithms are developed and utilized for the map-matching according to probability and statistical theories.Furthermore,road segment velocity matching methods based on the Metropolis criteria is extended and relevant validation is carried out through the comparison of estimated and measured results.The major objective of this method is to obtain more accurate road segment travel time through the combination those estimated by FCD and historical ones.This can significantly improve the reliability of instantaneous traffic information before its web publication.Finally,this paper introduces the architecture and the realization of a web Geographical Information System(GIS) and FCD-based instantaneous traffic information dissemination system for the whole of Shenzhen City.