External decorative mortar system and construction process thereof

The invention provides an external decorative mortar system with excellent efforescence resistance, stain resistance and weather resistance. The decorative mortar system comprises a base coat, a decorative mortar layer and a finishing varnish layer, wherein the base coat and the finishing varnish layer use latex containing organic silicon resin as a film forming material. The decorative mortar system ensures that the decorative mortar is separated from a base material and the external environment through the base coat and the finishing varnish layer which are arranged inside and outside the decorative mortar layer; and the base coat and the finishing varnish layer which adopt the latex containing the organic silicon resin as the film forming material not only can maximally reduce contact between mortar and moisture so as to fundamentally eliminate the condition of efforescence generation, but also can ensure ventilation of the whole system so as to better prolong the service life of the decorative mortar. The system and the process maximally reduce the manufacturing cost of the decorative mortar system while ensuring efforescence phenomenon prevention in a process of using the decorative mortar, excellent stain resistance and weather resistance, through synergic action of the base coat, the decorative mortar layer and the finishing varnish layer. The invention also provides the construction process for the external decorative mortar system.