Located in Wuhai City of Inner Mongolia, the Wuda coalfield is the biggest coal fire area in China. Between 2006 and 2008，shallow open-cut surface mining in the Wuda coalfield was conducted，with more than 2 000 million tons of coal excavated and more than 70% of the original landscape replaced by countless huge excavated pits and chip ballasts. If heavy rainfall occurred in the summer of 2009，the severely damaged coalfield would encounter floods，which would severely affect the safety and production of the coal mine. The relevant authorities paid a close attention to this problem. Using remote sensing (RS)，Global Positioning System (GPS)， Geographic Information Systems (GIS) and other new technologies in combination with some field work， the authors obtained a lot of investigation data and submitted an assessment report on the flood risk within 3 months. This is a successful practice of the application of 3S technology to the coal mine production.