The ZnO nanoparticles are prepared by a precipitation process, and also are characterized by means of the modern testing techniques such as XPS, ESR, SPS and PL. The activity of the as-prepared ZnO is evaluated in the photocatalytic oxidation of gas phase n-C7H16. The relationships of surface oxygen vacancies (SOV) with photoluminescence (PL) and photocatalytic performance are discussed in details. The results show that the smaller the particle size, the larger the SOV content, the stronger the PL signal, the higher the photocatalytic activity, indicating that the SOV, PL and photocatalytic activity have inherent relationships. This was because of the reasons that the PL signal is attributed to the free and binding excitons resulting from the SOV, while the SOV is favorable for a photocatalytic oxidation reaction since the SOV can easily capture the photoinduced electrons, and the captured electrons had strong interactions with the adsorbed oxygen. In addition, the surface states of ZnO nanoparticles, arising from the SOV and oxygen species, are very abundant.