Abstract: Slotted pipe drainage is a new drainage technology of tailings dam. Based on Darcy′s seepage law，mass conservation law，drainage and depressurization principle of filter layer，the calculation method and drainage mechanism of slotted pipe are explored by theoretical analysis and summarizing the previous studies. The system′s equivalent radius of the filter layer and the general seepage draining equation are deduced by establishing the theoretical calculation model. Then，the rationality of the theoretical research is verified through engineering examples.

Key words: Tailings dam, Slotted pipe, Drainage mechanism, Calculation method