Abstract: The calculation method for multicomponent square cascades was proposed. The method was based on the difference in the iteration sequence and iteration approach, and the mixing scheme of materials at stages was used as a constraint condition of the convergence. Numerical calculations indicate that the results obtained by the method and other methods were consistent. The method was very stable, and its convergence accuracy was independent of the initial iteration abundance, the cascade length and the overall separation factor. In addition, the method can be generalized to calculating complex cascades such as square cascade with additional flows, square-off cascade and multi-layer cascade.