Abstract: g-C₃N₄ nanosheet was obtained from the precursors melamine and BiOBr nanosheets was synthesized from the raw materials Bi(NO₃)₃·5H₂O and KBr. The two-dimensional g-C₃N₄/BiOBr heterojunction was synthesized by hydrothermal method. The intimated interface and suitable crystal facets of g-C₃N₄ and BiOBr were favorable the combination of this two photocatalysts, resulting in enhancing the visible-light photocatalytic activity. The phase structure, optical absorption property as well as composition and structure of as-prepared materials were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflection spectroscopy (DRS) and photoluminescence emission spectroscopy. The potential mechanisms of constructing two-dimensional g-C₃N₄/BiOBr heterojunction were revealed. The photocatalytic activity of as-synthesized photocatalysts was evaluated by photocatalytic degradation of RhB under visible light (λ>420 nm) irradiation. Results show that the as-synthesized heterojunctions can significantly enhance photocatalytic activity in comparison with pure g-C₃N₄ and BiOBr. The mechanisms of enhanced photocatalytic performance were explained.