The present invention is a cascade water supply structure of plants, including plural aqueducts, wherein at least one aqueduct is connected to a water supply end. Besides, the porous bodies are provided in soil close to roots of the plants and the porous bodies are connected in cascade by the aqueducts. The porous bodies are collaboratively provided in a receiving unit which is installed on an outer wall of a building. By the aqueducts, water from the water supply end is guided into each porous body and is permeated into soil by the capillary action of the porous bodies, allowing soil to keep humid constantly that the plants can be grown without being watered for a long time, saving manpower and cost.
