Abstract: It is necessary to carry out calculation and analysis of nonlinear flow field for better understanding the influence of the baffle and scoop on the separation of gas centrifuge. A finite difference method was used to calculate the strongly rotating flow field, using Newton-Raphson scheme to solve the steady Navier-Stokes equations for the Iguassu model centrifuge. Then the separation performance was obtained by solving the nonlinear concentration equations with numerical method. The analysis of the influence of the drive parameters on the separation performance and the comparison of linear and nonlinear flow fields indicate again the necessity of computation of nonlinear flow field. The flow field around the waste baffle plate shows clearly the difference between the linear and nonlinear methods, which causes the difference in the separation performance.