[en] Graphical abstract: - Highlights: • The g-C_3N_4/V_2O_5 heterocrystals are prepared by one-pot method. • V_2O_5 nanoparticles with diameter of 5 nm intertwined with g-C_3N_4 nanosheets. • G-C_3N_4/V_2O_5 heterocrystals showed excellent photocatalytic activity. • The possible photocatalytic mechanism was discussed. - Abstract: The g-C_3N_4/V_2O_5 composites with visible light photocatalytic performance have been prepared by one-pot method. The g-C_3N_4/V_2O_5 composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), thermogravimetric analysis (TG), UV–vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, Brunauer–Emmett–Teller (BET) and X-ray photoelectron spectroscopy (XPS). The results indicated that, within the g-C_3N_4/V_2O_5 composites, V_2O_5 nanoparticles were highly crystallized and intertwined with the lamellas of sheet-like g-C_3N_4 materials, resulting in the generation of well-defined heterostructures. The photocatalytic activity of the g-C_3N_4/V_2O_5 composites was evaluated using Rhodamine B as a target organic molecule. Under visible light illumination, as-prepared g-C_3N_4/V_2O_5 hybrid materials demonstrated highly improved photocatalytic activity than g-C_3N_4 and V_2O_5 materials. The enhancement in visible-light-driven photocatalytic activity can be ascribed to the formation of heterojunctions between V_2O_5 and g-C_3N_4, which promoted faster electron–hole separation and favored more efficient charge transfer.