Precursor (ZnC2O4) was synthesized by solid state reaction at room temperature using Na2C2O4 and ZnSO4·7H2O as raw materials. Nano-ZnO was obtained by decomposing ZnC2O4 at 450℃ for 5h. The ZnO was characterized by XRD、FT-IR、TG、SEM and TEM. The results show that ZnO crystalline has an average size distribution of 5nm and good activity at photocatalysis degradation of acid bright yellow G with the best dosage of 0.3 g/L.