Abstract: The biodegradability index BOD5 / COD and the relative oxygen consumption rate (R%) of several kinds of industrial wastewater are determined in this paper.Based on the dynamic test results of the simulated biological oxidation pond treatment,the relative oxygen consumption rate is propsedas a biodegradability judge index which is faster and easier to be determined and nearer to reality than BOD5 / COD,and a linear regression equation of the correlation between the judge index and the COD removal rate of the biological oxidation pond treatment is developed.Thus a theoretical basis is provided for choosing the project of the biological oxidation pond treatment of wastewater and for estimating the effciency of the COD removal rate.