The Houpoao tin mine has three mining sections, i.e. the west, the central and the east, with the west section having been mined-out and the east section being the major production area. Because of extensive mine development workings, the total ground water flow rate ranges from 500 to 600 m3/h. For ruduction of the flow rate fron mined-out area, a wallmay be constructed. In the paper, the wall constructing method is discussed including the site shape, relevant parameteras , struc-ture and building materials. Being simple and reliable, the method is a cost effective measure for sealing water flow.