Disclosed is a roof greening and environmental protection self-watering system based on rainwater recycling technology. The system comprises a transverse rod (1), vertical columns (2), flowerpots (4), a watering pipe (6) and a water storage tank (8), wherein the several vertical columns (2) are uniformly arranged at a bottom end of the transverse rod (1), the water storage tank (8) is arranged below the transverse rod (1), and the several flowerpots (4) are uniformly arranged above the transverse rod (1). Several first support rods (3) are uniformly arranged at a bottom end of each flowerpot (4), a separation net (43) is arranged on the bottom of an inner cavity of each flowerpot (4), and the separation net (43) separates the inner cavity of the flowerpot (4) into an upper cavity and a lower cavity. A sand-gravel layer (41) and a soil layer (42) are provided in the upper cavity, and the soil layer (42) is provided in an inner hole of the sand-gravel layer (41). The watering pipe (6) is arranged above the flowerpots (4), several second support rods (5) are uniformly arranged at a bottom end of the watering pipe (6), and several drip nozzles (7) cooperating with the flowerpots are uniformly arranged on the watering pipe (6).