External wall thermal insulation system

The utility model discloses an external wall insulation system. Relating to the technical field of building materials, foundation wall, a heat preservation layer and a surface coating layer are sequentially arranged on the outer side of the foundation wall body. The heat preservation layer and the foundation wall body are bonded through a first mortar layer, and the heat preservation layer and thesurface coating layer are bonded through a second mortar layer. The heat preservation layer and the foundation wall body are fastened through expansion anchor bolts. The heat preservation layer is composed of two layers of extruded polystyrene boards which are attached to each other, a plurality of through holes are formed in each layer of extruded polystyrene board, the through holes in the twolayers of extruded polystyrene boards are arranged in a staggered mode, a plurality of water storage grooves are formed in the attached surfaces of the two layers of extruded polystyrene boards respectively, and the water stor