The invention discloses a COD-based rain and sewage pipe network intelligent splitting device, which comprises a control box, a sewage pump, a liquid level gauge, a COD concentration sensor, an intelligent control system, and an intelligent control system for controlling the start and stop of the sewage pump; the intelligent splitting device comprises a control box, a sewage pump, a liquid level gauge, a COD concentration sensor and an intelligent control system. At least two liquid level data and one COD concentration data are preset in that intelligent control system, which are mar as the starting liquid level, the close liquid level and the opening / closing concentration respectively, and the closing liquid level is higher than the top elevation of the sewage pump; When the liquid levelis higher than the starting liquid level and the COD concentration data is higher than the on-off concentration, start the sewage pump to work; If the COD concentration data is less than the on-off concentration, or the liquid level measured by the level gauge is lower than the off-off liquid level, the sewage pump shall be switched off. The invention can realize the secondary collection of sewage; Can collect initial rainwater, reduce pollutants into the river; Intelligent control system, which can realize automatic rainwater and sewage distribution; Flood discharge and drainage will not be affected.