Abstract: Taking 1128 working face filled by high-water-content material in Xingdong coal mine，Jizhong Energy Resources Co.，Ltd. as research object，and through analyzing the filling method with high water material，testing physical and mechanical characteristics of high water material such as internal structure，unit weight，moisture content and volume strain by scanning electron microscope (SEM) and MTS in the laboratory，roof activity patterns and floor failure depth under the reaction of high water material and rock strata were researched combining with the field test data in filling working face.The results showed that filling efficiency in mined-out area was greatly improved when high water material was transported by pipes and adopting the hybrid-type filling method.High water material has good plasticity.With the increase of water-cement ratio，the material′s compressive strength decreased，and volume strain increased，and the material′s plasticity performs more obvious; When the underground goaf was filled by high-water material，stress state in surrounding rock was changed.The perturbations distance in front of working face was about 27.7 m，and the maximum failure depth in floor strata was about 22 m.The filling mining with high-water material decreased floor failure depth，shortened the perturbations distance ahead of working face and effectively controlled ground pressure′s behaviors.

Key words: High-water material, Goaf filling, Physical and mechanical characteristics, Volume strain, Roof and floor strata