Abstract: Using the Parabolized Stability Equations (PSE), the nonlinearevolution of Stationary crossflow vortices over a swept NLF0415(2) airfoilis studied, then Floquet theory is employed to systematically study thedependence of the secondary, high-frequency instabilities on the curvatureat different conditions. Haynes (2000) shows that the curvature has astabilizing effect for linear stability theory and nonlinear ParabolizedStability Equations, and the results show that the curvature has no effectfor secondary linear stablity equations.