N-doped TiO2 nanoparticles deposited on reduced graphene oxide sheets were successfully prepared by a photoreduction method. The synthesized N-TiO2/rGO composite was characterized by XRD, SERS, XPS, TEM, UV–vis DRS and PL, and its visible-light photocatalytic activity was evaluated by degradation of tetracycline hydrochloride (TC). The results showed that N-TiO2/rGO composites exhibited a more enhanced photodegradation activity compared to pure TiO2 and N-doped TiO2. Trapping tests indicated that not OH and h+ but O2− was chiefly responsible for the photodegradation process. The reusable experiments showed that the prepared N-TiO2/rGO catalyst was stable during the photodegradation of TC.