Abstract: Drag reducing agents（DRA） can reduce the frictional pressure drop of turbulent fluid in the pipe and improve the flow of fluid without change the condition of the pipeline operation mode.DRA indoor loop equipment，which was similar to a company′s actual phosphate concentrate slurry pipeline，was designed to simulate，and evaluate the drag reduction property. The factors on drag reduction property were studied by DRA species，DRA concentration，and fluid Reynolds number，and the optimal conditions were as follows：at room temperature（25 ℃），polyacrylamide mass concentration（mass of DRA per unit volume of slurry，mg/L） was 500 mg/L，and Reynolds number was 14 154（corresponding flow rate of fluid was 2.21 m/s）. Under these conditions，the flow of phosphate concentrate slurry increased from 2.31 m3/h to 3.36 m3/h，with 45.6% improved.

Key words: indoor loop, DRA, polyacrylamide, reynolds