Uniformly nano-sized macroporous silica consisting of well-defined pore sizes were successfully fabricated. A modified sol-gel process, using mono-dispersed polystyrene(PS) spheres as templates, was employed for configuring three-dimensionally ordered macroporous structure. The nano-sized macroporous silica structure was formed when the templates were removed by the calcination at high temperature. The pH value affected uniformly stacked order in the PS/silica matrix due to the PS being uniformly coated by silica film at appropriate pH value. Also this pH value affected the iso-electrics points between the PS and silica particles surface charges. The heating temperatures and the reaction times were considered to conform the microstructural morphology, the thermal deposition of organic components, the matrix wall thickness and densification behavior. Three-dimensionally assembled porous silica consists of uniform-sized pores of 200nm and high specific surface area of 163 m2/g.