Abstract: In order to reduce the pipe wear of a certain iron ore backfilling pipe,decrease the risk of pipe blockage, eventually achieve to optimize the underground pipe network, the grain size analysis test，caving degree test and L type pipe fluidity test were conducted, to study the flowability of the full tailings backfilling slurry in the iron ore. From the above experiments, the concentration and rheological parameter of structure fluid could be determined. Through the analysis， on-way resistance of gravity transportation slurry in different diameter could be calculated.Then the optimal location of the deepening pipe network is obtained. Result shows that whole tailings particle size is fine，the average particle size is 51.6 μm. When the filling slurry concentration is 72% ~ 70%, the corresponding caving degree is 28.6~27.3 cm, yield shear stress τ0 is 3.690~1.471 Pa, viscosity coefficient is 0.701~0.450 Pa·s. The test process and results can be determined the slurry concentration range of structure fluid state is 72% ~ 70%. Optimization on the deepening parameter of backfilling pipe network for deep level ore body mining, when slurry concentration is 72%，the flow resistance along the path is 1.420～1.893 kPa/m，the placement range of filling patio L should be 631~673 m. Then， the self-flow transport of structural fluid slurry can avoid a series of downsides， suchas the disadvantages of low full-flow ratio and serious pipe wear.

Key words: Flowability, Structural fluid, Backfilling pipe network, Pipe wear, On-way resistance