Abstract: Solving the static characteristic roots of hydraulics in isotope separation by centrifuge cascades is an important problem. The paper adoptes the method used in diffusion cascades in order to obtain the complete 4 static characteristic roots in centrifuge cascade. The method solves the hydraulics equations with pressure excursion equation. Comparison with the diffusion cascade shows that they both have 4 roots, while the 2nd root is main characteristic root and the 4th one Z₄=1 comes into play only when there exists a feed. Finally, two solution approaches to static characteristic roots, the pressure excursion and the flux excursion, were also compared in the paper. For the centrifuge cascade without any feed, the two approaches can obtain the same static characteristic roots.