Micrometer-sized mesoporous silica SBA-15 spheres with good dispersivity were successfully synthesized by adding the soluble starch into the aqueous solution containing P123 and tetraethyl orthosilicate, based on the special function of water-soluble polymer in the sol-gel process. The obtained SBA-15 silica spheres were characterized by scanning electron microscopy, X-ray diffraction and N2 physisorption technique. The obtained SBA-15 spheres possessed pore size from 17.4 nm to 24.3 nm and the specific surface area from 565.3 m2 g-1 to 459.4 m2 g-1. Furthermore, the dispersibility of SBA-15 silica spheres was good. The results showed that appropriate amount of soluble starch improved the uniformity and dispersibility of silica spheres, while the structure and pore size of the obtained SBA-15 silica spheres with hexagonal symmetry created by P123 remained unchanged.