Abstract: The TiO2 nanoparticles capped with sodium dodecylbenzenesulfonate (DBS) were synthesized by a sol-hydrothermal method, and were also characterized by XRD, TEM, Surface Photovoltage Spectroscopy (SPS) and Photoluminescence (PL). The effects of capping DBS on photovoltage and photoluminescence performances of TiO2 nanoparticle as well as appropriate capping conditions were principally investigated. The results show that the capping situation is desirable when the pH value and adding DBS amount are in the range of 4.5-5.5 and 1.0%-3.0% of TiO2 weight in advance of the hydrothermal process, respectively. The added DBS could inhibit the growth of anatase crystallite during the hydrothermal process. Moreover, the intensities of SPS and PL of TiO2 nanoparticle decreased after DBS was capped, which is possibly attributed to the electrophilic property of sulfonic acid group (-SO3-) as well as the decrease of surface defect.