A novel multidimensional heterojunction, the 1D trigonal Se nanorods (t-Se NRs) dissociated from CdSe QDs germinating on the 2D BiOCl ultrathin nanosheets, was successfully synthesized via a facile hybridization method. Such unique nanocomposite served as an efficient visible-light-driven photocatalyst for the photodegradation of the tetracycline hydrochloride (TC-HCl) solution. The obviously enhanced photocatalytic performance compared with pure BiOCl was mainly attributed to the introduction of Se NRs, which greatly enhanced the optical absorption in visible-light region and suppressed the recombination rate of electron-hole pairs by steering the charges migrating in a special manner. Specially, t-Se NRs in BiOCl system played an integral and important role as holes transfer channels, impelling more photogenerated electrons of BiOCl to participate in the photocatalytic process. Reactive species trapping experiments indicated the main reactive species were center dot O-2(-) radicals, which were generated by the collisions of excited electrons and molecular oxygen. Meanwhile, the radically increased ESR peak of center dot O-2(-) radicals for the heterogenous materials demonstrated successful release of abundant high-energy electrons. This work could be extended to the design of other robust 1D/2D heterojunction photocatalysts in application to the environmental demands.