The present disclosure provides a method for collecting and further reducing phosphorus by kidney-inspiration in a slope catchment area of a phosphorus-rich area. The method includes the following steps: analyzing suspended solids, total phosphorus, dissolved phosphorus, and total nitrogen in the surface runoff of the phosphorus-rich area through the hydrometeorological assay report； determining the amount of fillers and plants required based on the rainfall and the concentration of relevant non-point source pollutants； determining the scale of the desilting and filtration system based on the obtained rainfall and suspended solids content； designing the size of the catchment/drainage ditch according to the rainfall； the runoff and hydraulic parameters such as hydraulic retention time； hydraulic load； flow rate； and flow velocity. The present disclosure mainly solves the problem of the loss of nitrogen and phosphorus output from the mountainous phosphorus-rich area. In order to prevent and control the loss of nitrogen and phosphorus, the earth-rock engineering and the biological engineering are combined into a micro-ditch shunting/infiltration system and a drainage/confluence system； so as to eliminate the pollutants in the catchment area in situ. The present disclosure is applied for removing non-point source pollutants such as total suspended solids (SS), phosphorus (P), nitrogen (N) in the runoff of the mountainous phosphorus-rich areas.
