Abstract: Three kinds of coefficients are defined and introduced into the basicequations for meridional throughflow fields in multistage axial- flow compressors deduced by the authors which describe different kinds of spanwise mixing mechanism in a unified form. Then, a novel much simpler equation system is obtained without any unknown correlation terms included. It has been shown that these coefficients involve the full information of all the kinds of mixing mechanism. This novel equation system not only unifies the two analytical models for meridional throughflow with mixing which were presented by Adkins and Smith (1981) and Gallimore and Cumpsty (1986) respectively, but also makes the computations for multistage machines much easier. The calculations of the flow through multistage machines have been made by incorporating the new model into a streamline curvature throughflow calculation method. The agreement of the calculation results with experimental data has been improved. It is believed that this simpler equation system can be applied to the flows not only in subsonic compressors, but also in transonic and supersonic compressors, provided that a more appropriate model is proposed for the coefficients.