With the continuous development of Intelligent Transportation System (ITS), amount of data can be collected, generated and used by ITS, and the application of big data technology in Intelligent Transportation System is also applied in different kinds of fields. This paper first explains the definition of big data and intelligent transportation systems. Second, the framework of big data technology in the Intelligent Transport System (ITS) is introduced, which summarizes the data collection methods in specific scenarios of ITS, the application methods of data analysis in ITS, and the application of big data technology in ITS. Furthermore, this paper introduces several case studies on the application of big data technology in ITS, including public transport service planning, road traffic flow prediction, road traffic accident analysis, personal travel route planning, rail traffic management and control, and data analysis and prediction of bridge safety. Finally, this paper discusses some challenges of using big data technology in ITS.