Micrometer-sized silica spheres with uniform spherical morphology and highly ordered mesostructures were synthesized by a temperature-induced and polyethylene glycol (PEG)-assisted assembly method. A modified and convenient incipient wetness impregnation method was then presented, and high performance adsorbent with silver nitrate (AgNO3) supported on micrometer-sized mesoporous silica spheres was prepared. The characteristics of adsorbing benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-Me2DBT) from n-octane solution on the adsorbent were studied, and the equilibrium absorption data were described with the Freundlich equation and the Langmuir equation separately. The experiment of adsorptive desulfurization was also carried out in fixed-bed, and the results showed that the adsorption capacity reached as high as 20.5 mg S/g of adsorbent for DBT.