In this paper, Z-scan characteristics of the cascade structure of nonlinear media are analyzed, analytic and numerical solutions are obtained. Analytic analysis is based on the combination of Gaussian decomposition method (GDM) with the distributed lens method, and numerical calculation is based on the Crank-Nicholson finite difference scheme and fast Hankel transformation. Meanwhile, the conditions and method to apply these two numerical analyses are also given. Comparing analytic solutions with numerical calculation and experimental results, it is shown that they agree very well with each other.