Novel 3D P-doped poly(triazine imide) (PTI) nanotubes were prepared in situ by molten salt method with melamine and hexachlorotriphosphazene as starting precursors. The as-prepared composite showed superior photocatalytic properties under visible-light irradiation due to the integrated merits of 1D tubular structure, 1D nanorods, and P doping. The improved utilization of visible light and the enhanced separation of photo-induced charge carriers resulted in the maximum degradation rate constant of P-doped PTI at 2.86 min(-1), which was approximately 6.3 and 2.6 folds those of bulk graphite-like carbon nitride and pristine PTI material, respectively, during tetracycline hydrochloride photodegradation. Moreover, the novel catalyst has an excellent stability and thus is a promising candidate for photocatalysis.