The invention discloses a reflective and heat-insulating outer wall architectural coating and a preparation method thereof. The reflective and heat-insulating outer wall architectural coating includes, by weight parts, 40-60 parts of epoxy modified acrylic emulsion, 20-30 parts of hollow glass microbeads, 15-25 parts of rutile type titanium dioxide, 5-10 parts of infrared reflective agent, 4-8 parts of heat-insulating reflective material, 5-10 parts of mica powder, 3-6 parts of precipitated barium sulfate, 2-8 parts of iron oxide red, 1-5 parts of functional materials, 0.5-1 part of wetting dispersing agent, 0.3-0.8 part of defoaming agent, 0.4-0.8 part of thickener, 0.3-1 part of film forming aid and 15-30 parts of deionized water. The reflective and heat-insulating outer wall architectural coating has good heat insulation, and can block heat to the outside, thereby suppressing the heating of a building. The higher the outdoor temperature, the more obvious the effect of heat insulation and cooling. Compared with an ordinary coating, the actual indoor and outdoor temperature difference can reach 11-15 DEG C.