The invention discloses a thick plastered exterior wall outer heat-insulation system with double-layer gridding cloth compounded with foam cement boards. The thick plastered exterior wall outer heat-insulation system comprises an interface layer, a leveling layer, an adhesion mortar layer, a heat-insulation layer with the foam cement boards, an anti-crack protective layer with the inlaid double-layer gridding cloth and a finishing layer. The interface layer, the leveling layer, the adhesion mortar layer, the heat-insulation layer with the foam cement boards, the anti-crack protective layer with the inlaid double-layer gridding cloth and the finishing layer are sequentially fixedly connected with one another from the inside to the outside on the basis of a base-layer wall, joint filling and leveling heat-insulation materials are embedded in gaps of the foam cement boards in the heat-insulation layer with the foam cement boards, and the anti-crack protective layer with the inlaid double-layer gridding cloth comprises first gridding cloth, anchoring parts, second gridding cloth and three layers of anti-crack mortar. The thick plastered exterior wall outer heat-insulation system has the advantages that common quality problems of plate marks, anchor bolt marks, cracks and the like of a thin plastered system can be solved, the anchoring parts are assuredly positioned on the outer side of the gridding cloth, performance indexes of the wind load resistance, water absorption, impact resistance and the like of the outer heat-insulation system are increased, and the safety of the system is improved.