The utility model relates to a coastal saline-alkali soil greening alkali discharging system. The coastal saline-alkali soil greening alkali discharging system comprises an alkali soil layer on the bottom, a planting soil layer at the top and an alkali discharging layer between the alkali soil layer and the planting soil layer. An alkali discharging ditch is formed in the alkali soil layer, and an alkali discharging pipe is arranged in the alkali discharging ditch. Holes are formed in the surface of the discharging pipe which is connected with an alkali discharging collecting well. Besides, the outer surface of the alkali discharging pipe is wrapped by geotechnical cloth. The geotechnical cloth has excellent filtering and drainage performance, high permeability and strong corrosion resistance, and thus the alkali discharging pipe wrapped by the geotechnical cloth not only can ensure that alkaline seeped water can be collected in the alkali discharging pipe, but also can effectively filter large particulate matter such as silts carried by the alkali seeped water through the geotechnical cloth on the surface of the alkali discharging pipe. Thus, a normal alkali discharging function of the alkali discharging pipe is ensured, and meanwhile, silting of the alkali discharging pipe is effectively prevented.