Hydrophilic Ti-MCM-41 was modified by alkylsilyl groups using n-octadecyltrichlorosilane as the precursor, yielding an amphiphilic molecular sieve denoted as OTS-Ti-MCM-41. The sample retained mesoporous structure and morphology, as confirmed by XRD, N-2 adsorption-desorption, and SEM. The presence of surface alkylsilyl groups was confirmed by infrared spectroscopy. The amphiphilic OTS-Ti-MCM-41 located at the boundary between aqueous and organic phases acted as a phase-boundary catalyst for the photooxidation of dibenzothiophene (DBT) without the need of adding a co-solvent to drive liquid-liquid phase transfer. With H2O2 as the oxidant, the conversion of DBT on OTS-Ti-MCM-41 was up to 98% at 2 h, much higher than that on Ti-MCM-41. When air was used instead of H2O2 as the oxidant, the conversion of DBT on OTS-Ti-MCM-41 was up to 85% at 2 h.