Abstract: With the rapid development of economics and urban integration in coastal areas, the amounts of wading constructions such as sea-crossing bridges and natural disasters-prevention sea-walls increase faster. However, in tidal race waters, severe sectional scour induced by tidal flows often appears around marine structures and has been the main threat to those marine structures. Hence, the real-time monitoring and the study of sectional scouring of bridge piers and seawalls become the key to solve the difficulties. We analyzed the applications as well as the strengths and shortcomings of former technologies of scouring monitoring, so then studied and developed the fixed-point multi-beam echo sounder monitoring system of real-time. The system offers underwater topographic data of real-time time serials and full coverage, and also supports the study of scouring as well as the prevention and reduction of disasters in wading constructions through those data. We also proposed a fitting formula from the data observed by the system that provides with a method for calculating the scour depth, so as to support the study of souring mechanism and the forecast of scouring process with key basic scouring data and a calculating method.