ZnO/g-C3N4 composite was prepared by one-step calcining.The microstructure and absorption property of the as-prepared samples were characterized by XRD，SEM，TEM，FT-TR，and UV-vis DRS.The results showed that ZnO particles distributed uniformly on the surface of g-C3N4，and the light absorption edge of the composite had an obvious red shift compared with pure ZnO.Photocatalytic degradation of methyl orange solution experiments was conducted to evaluate photocatalytic activities of the as-prepared samples.The results indicated that ZnO/g-C3N4 exhibited higher photocatalytic activity than pure ZnO and pure g-C3N4.The photocatalytic efficiency was 14 and 9 times as high as that of ZnO and g-C3N4，respectively.The photocatalytic performance of the composite got promoted mainly due to the formation of heterogeneous structure between ZnO and g-C3N4，which decreased recombination rate of photo-induced electron-hole pairs.Furthermore，the composite had wider photoabsorption region compared with pure ZnO，which increased utilization rate of solar energy.