Abstract: Based on the property of the ultra high water material,the features of the backill mining technology with the ultra high water material was studied.The te chnology was including the open type,full package type,mixed type and other mining goaf backfill method.The backfill technical system was composed with material stor age and transportation,slurry preparation,slurry transportation,slurry mixing,and the backfill technical system was applied to several mines.The application results show ed that the ultra high water material had a high water content(water volume reached at 95%97%),fast setting rate(initial setting time of 890 min),high early strength,cons olidate incompressible,good loading performances,controllable material strength and setting time and other excellent performances and could be a good backfill material of the mining goaf.The backill technical system would have a low initial investment(not over RMB 5.0 millions),simple operation,high automatic degree and low pipelin e abrasive wear.After the backfill mining conducted,the backfill rate of the mining goaf was over 85% in average,the mine strata pressure behavior degree of the coal mi ning face was obviously reduced,the failure grade of the surface buildings was within grade I failure scope stipulated by the state.