A new method is proposed in this paper to predict the critical pressures of hydrocarbon mixtures by reversely using the Riedel equation which is used for calculating vaporization heat. The parameters used in the calculation are boiling temperature, critical temperature, critical volume and vaporization heat of the pure substances. The reliability of the method is discussed on the basis of the results obtained by predicting the critical pressures of many binary hydrocarbon-hydrocarbon and hydrocarbon-non-hydrocarbon mixtures. The proposed method is rather simple and can be used for rapid estimation of the critical pressures of hydrocarbon mixtures.