Octaphenylsilsesquioxane (OPS) and Octa(nitrophenyl)silsesquioxane (ONPS) were synthesized by a conventional approach. The structure was characterized by FTIR, GPC, 1H NMR and 29Si NMR. Then ONPS was added into the latex to modify polyacrylic ester (PAE) emulsion. The compatibility, mechanical and thermal properties of modified PAE emulsion were investigated through di.erential scanning calorimetry (DSC), the tensile strength tester and transmission electron microscopy (TEM) micrographs.The studies on TEM and the particle size distribution showed that the Octa(nitrophenyl)silsesquioxane particles homogeneously disperse in the emulsion at a nanometer scale. Differential scanning calorimetry showed that the addition of ONPS increased Tg of PAE emulsion significantly. The tensile strength of films increased with the addition of ONPS, but rupture elongation decreased slightly. The general properties obtained optimum when the content of ONPS was 2∼3%.