The invention relates to a ceramic glaze, in particular to a nano phase separating self-cleaning glaze of ceramic out-wall bricks. The material composition (wt percent) is as follows: 26 to 32 percent of glaze quartz, 0 to 3 percent of glaze feldspars, 3 to 4 percent of Suzhou clays, 30 to 46 percent of high titanium blast furnace slag and 20 to 38 percent of FT818 frits; the chemical composition (wt percent) is as follows: SiO2: 54.22 to 63.16 percent, Al2O3: 8.22 to 11.18 percent, Fe2O3: 0.24 to 0.36 percent, TiO2: 3.16 to 4.69 percent, CaO: 10.11 to 13.24 percent, MgO: 4.28 to 5.90 percent, ZnO: 3.30 to 5.61 percent, BaO: 0.20 to 0.40 percent, K2O: 1.41 to 2.35 percent, Na2O: 0.52 to 0.97 percent, Li2O: 0.20 to 0.39 percent, B2O3: 0.45 to 1.76 percent , and ZrO2: 0.41 to 1.72 percent. After the glaze of is fired, nanometer protuberances and nanometer TiO2 clusters form on the surface of glaze, and the ceramic glaze is good in super-hydrophilic property, high in photocatalysis efficiency, good in anti-soil effect of the glaze surface and has self-cleaning function; and especially the high titanium blast furnace slag is taken as the main material, thus realizing waste utilization and decreasing costs.