The invention discloses an energy-saving decoration system of a composite radiated heat-insulation film and a construction method thereof. The energy-saving decoration system is connected with a building surface, a radiated heat-insulation film, a steel plate expansion net, caking property polymer mortar, an interface curing agent, an alkali-resisting self-adhesion fiber fiberglass mesh, crack-resistance polymer mortar and a decorative surface course in order from the building surface to the outside, wherein the alkali-resisting self-adhesion fiber fiberglass mesh is laid out of a bond course; and a crack-resistance polymer mortar layer is solidified and combined with the outer surface of the alkali-resisting self-adhesion fiber fiberglass mesh to form a crack-resistance layer of which the outer surface is connected with the decorative surface course. One or two layers of inner caking property polymer mortar are provided; a second layer of interface curing agent is coated between the crack-resistance polymer mortar and the decorative surface course; and the decorative surface course is made of a coating, wallpaper, tiles, glass or stone. The energy-saving decoration system is convenient in material construction and small in occupied space, can effectively obstruct heat conduction, heat convection and heat irradiation, reduces the influence of the external thermal environment in a building on the indoor thermal environment in the building, saves building energy consumption and can be widely applied for thermal insulation construction for buildings.