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Hollow B-SiO2@TiO2 composites were prepared by the wet chemical deposition method starting from TiCl4 and hollow B-SiO2 microspheres. TiO2 layers composed of anatase TiO2 nanoparticles were coated on the surfaces of the hollow B-SiO2 microspheres probably through the formation of Ti--O--Si and Ti--O--B bonds. A great num-ber of--OH groups were also present at the TiO2 coating layers. The presence of Ti--O--Si bonds and Ti--O--B bonds resulted in the formation of defects in the TiO2 coating layers, which decreased the band gap of the TiO2 coating layers to ca. 3.0 eV and endowed the TiO2 coating layers with visible light absorption performance. The buoyancy hollow B-SiO2@TiO2 composites exhibited high photocatalytic activities for the degradation of ammonia-nitrogen and green algae. The conversion of ammonia-nitrogen reached 65％when the degradation of ammonia-nitrogen (43 mg·L?1 at pH value of 8) was catalyzed by the B-SiO2@TiO2(100:10) composite under the simulated solar light irradiation at 35 °C for 660 min. The green algae (5 mg·L?1) were almost completely degraded over the B-SiO@TiO2(100:20) photocatalyst under the visible light irradiation at 35 °C for 510 min.