Abstract: Compared with traditional backfill materials, Performance-controlled fluidized solidified backfill material have the characteristics of high flow state and self-compaction, which can effectively avoid engineering problems caused by insufficient compaction, especially for backfill in narrow areas. Using silt as raw material and cement as curing material, PCFS material with controllable properties such as strength, fluidity and setting time is prepared. The influence of different initial conditions on the fluidity of PCFS was discussed through the flow test. In order to improve the flow performance of PCFS, three water reducing agents, calcium lignosulfonate, naphthalene superplasticizer and polycarboxylate superplasticizer, were selected, and the effect of three water reducing agents on improving the flow of PCFS was compared and analyzed. The results show that there is a positive linear correlation between the fluidity of PCFS and the initial water content. The addition of cement will lead to a significant decrease in the fluidity of PCFS, which mainly occurs when the cement content is less than 2%. The increasing range of PCFS fluidity of the three water-reducing agents was from large to small in the order of polycarboxylate superplasticizer > naphthalene superplasticizer > calcium lignosulfonate, wherein the incorporation of polycarboxylate superplasticizer and calcium lignosulfonate would introduce bubbles, and the "saturated content" of naphthalene superplasticizer and calcium lignosulfonate was 2% and 4%, respectively. The different cement content will make the three kinds of water-reducing agent to improve the flow effect has a significant difference. The increase of cement content reduces the effect of calcium lignosulfonate, has little effect on polycarboxylate superplasticizer, and shows an " anomalous effect " on naphthalene superplasticizer. Finally, the causes of "saturation content" and " anomalous effect " are discussed, and the fluidity expression formula of PCFS under the condition of initial water content 2wL and 5% cement content is proposed.