In order to enhance a strength and flowability of cemented filling materialswith unclassified tailings,the authors made the test for two types of dewatering agents,i. e. Type YJ-2 and High-Efficiency Type FDN, added to filling material, and analyzed the test results.It was noted that the suitable addition of Type YJ-2 dewatering agent can in-crease the 28d strength of cemented filling material with unclassified tailings and its flowa-bility.