Carrousel oxidation ditch has been widely used in sewage disposal system, however the result of sewage disposal was affected by water quality and environmental factors, so it is difficult to build a precise prediction model. The existing method of machine learning algorithm usually gets a poor result in prediction. In order to precisely predict the result, this essay uses the multi-kernel wavelet support vector machine when build a model. The outcome of this experiment demonstrates that the new method improve the degree of definition in forecasting, and it is suitable for actually online prediction.