An assembly well irrigation system for environmentally friendly water conservation includes: at least one well, having a ventilation tube inserted into the top of the well, an absorbent element covered onto the bottom and outer wall of the ventilation tube and filled up in an opening between the top of the well and the ventilation tube, and a float contained in the ventilation tube; and at least one water supply bottle, having a cover installed to the opening of the water supply bottle, and the cover having a fixed tube passing to the cover and a penetrating hole formed on the cover, and the penetrating hole having a movable tube capable of moving up and down for adjustment, and the water supply bottle being inverted, such that the cover is installed to the well, and the fixed tube, the movable tube and the ventilation tube are situated in the well.
