Abstract: Tailing sand consists of fine sand and other finegrained material from the mining wastes. The tailing sand discharged in to the tailing reservoir in the form of slurry and the engineering properties of this solid deposit have the characteristics of high moisture content, high void ratio. A new soil improvement method, which is the combination of pointwell dewatering and dynamic compaction, is introduced in this paper. This method has the advantages of short construction period and cost effective. This paper presents the soil improvement results of tailing sands in Dahongshan tailing reservoir. The site in-situ tests and monitoring results indicated that this is a very effective soil improvement method for the tailing sand materials. The project won the national first-grade award in the geotechnical investigation QC group.