The invention discloses a splicing type automatic water supply stereo greening device and an irrigation system thereof; the splicing type automatic water supply stereo greening device comprises a device body; a fabric guiding body is arranged in the device body so as to divide the device into an upper planting room and a lower water storage room connected together; the fabric guiding body uses the capillarity principle to realizing upper level plant automatic water supply; the irrigation system uses water fluidity to cooperate with a dual-interlayer pipeline so as to realize layered irrigation from top to bottom of the whole structure, and single body structure bottom-top irrigation mode is realized; the device is provided with a plant culture matrix material shield, thus fixing the shape of a medium; the top of the device is provided with an anti-insect cover so as to solve the airborne dust and mosquito breeding problems; the device planting zone is provided with bar shaped protrusion ventilating grooves so as to ensure effective breathing of the plant root and effective fixing of the medium. The splicing type automatic water supply stereo greening device is simple in structure, safe, convenient in planting, low in construction and maintenance cost, long in irrigation period, thus saving water resource, improving building thermal performance, providing an excellent plant survival environment, and preventing mosquito breeding; the device is suitable for indoor wall surfaces, outdoor building surfaces, viaducts, and slope protection, and is not affected by building height.