The invention relates to the technical field of building wall decoration, and particularly discloses a composite heat-insulation flexible facing sheet for a building wall and a processing technology and an application of the composite heat-insulation flexible facing sheet for the building wall. The composite heat-insulation flexible facing sheet comprises a soft porcelain facing layer and a heat-insulation bottom layer, and a toughening layer is arranged in the soft porcelain facing layer; the soft porcelain facing layer is prepared from the following raw materials: water, a dispersing agent, a defoaming agent, cellulose ether, an emulsion, blast furnace mineral powder, tailing slag, wollastonite powder, quartz sand, fibers, a thickening agent and pigment; the heat-insulation bottom layer is prepared from the following raw materials: water, cellulose ether, a wetting agent, a dispersing agent, a defoaming agent, a pH regulator, a cosolvent, a sterilizing agent, an emulsion, a water repellent agent, silicon dioxide aerogel, hollow glass beads and a thickening agent. According to the composite heat-insulation flexible facing sheet, through the synergistic effect of the glass fiber grid cloth, the soft porcelain facing layer and the heat-insulation bottom layer, the composite heat-insulation flexible facing sheet not only has good heat insulation and heat preservation performance, but also has the advantages of being light in self weight, good in flame retardance, good in flexibility, good in durability and easy and convenient to construct.