The invention relates to an energy-saving building external wall thermal insulation decorative plate. The decorative plate comprises a main body, two anti-falling mechanisms and two dust removal mechanisms, wherein each anti-falling mechanism comprises a fixing box, a suction pipe, a first spring, a driving assembly, a driving plate, a first magnet block and two second magnet blocks; the driving assembly comprises a first bearing, a branch pipe, a rotating pipe, a rotating rod, a cleaning unit and two fan blades, and the dust removal mechanism comprises a dust removal box, a dust removal pipe, a second bearing, an auxiliary assembly and a plurality of nozzles. The external wall thermal insulation decorative board of the energy-saving building reduces the air pressure in the notch through an anti-falling mechanism, so the main body can adhere to an external wall of a building, stability of the main body installed on the building outer wall is improved, the probability that the main body is disengaged is reduced, reliability of the equipment is improved, the dust removal function of the main body is achieved through the dust removal mechanism, cleanliness of the main body is guaranteed, attractiveness of the main body is improved, and practicability is higher.