Video event detection technology has become a hot issue in the Intelligent Transportation Systems(ITS) research. It mainly uses in highways, tunnels, urban roads and other video surveillance systems. This paper makes a brief overview on the development of video detection technology at home and abroad. It describes the working principles and key technologies of the two kinds of incident detection technology based on virtual detection loop and video vehicle tracking, compare above two technology to sum up their advantages and disadvantages. At last it introduces the typical products of the domestic and foreign video event detection technology, their applications and performance index.