The invention relates to inner wall composite nano paint. The paint consists of the following raw materials: nano composite material I, nano antibacterial powder, plasticizing agent, pure water, dispersant, antifreeze, defoaming agent, nano titanium dioxide, flatting agent, styrene-acrylic emulsion, filling, thickening agent and film forming additive, wherein based on the gross weight of the inner wall nano paint, the paint comprises 6.8 percent of the nano composite powder, 0.3 percent of the nano antibacterial powder, 2.8 percent of the intensifier, 0.3 percent of the dispersant, 2.5 percent of the antifreeze, 0.28 percent of the defoaming agent, 27 percent of the nano titanium dioxide, 0.5 percent of the flatting agent, 32 percent of the styrene-acrylic emulsion, 7 percent of the filling, 1 percent of the thickening agent, 2.2 percent of the film forming additive, and the balance being pure water; and the filling is fine particle calcium carbonate or coarse whiting. The inner wall antibacterial nano paint integrates the functions of heat insulation, fire retardation, heat preservation, environment protection, high elasticity and impact resistance.