Bi2O2CO3 modified graphitic carbon nitride (g-C3N4) nanosheeets were prepared by a simple one-pot synthetic strategy. In the presence of ammonium nitrate, different mass ratios of bismuth nitrate/melamine were used to fabricate these catalysts, which were characterized by XRD, N2-physisorption, FT-IR,TEM, XPS, UV-vis analysis, and PL. The catalytic properties of composites were evaluated by photodegrading tetracycline hydrochloride (TC) under visible-light irradiation. Among these catalysts, Bi2O2CO3(1.5)/g-C3N4 showed the highest catalytic activity, which was more than 16 times greater than the pristine g-C3N4 material. The improved photocatalytic properties of Bi2O2CO3/g-C3N4 may be due to the formation of a heterojunction between Bi2O2CO3 and g-C3N4, leading to the effective separation of photo-induced carriers and the enhanced absorption of visible light. Furthermore, the Bi2O2CO3/g-C3N4 composites had considerable catalytic stability, which was a key element for their potential applications.