Abstract: The clearance of modern flight control laws to take into account the m any uncertainties has become a great challenge to engineers and researchers, and traditional grid-based methods have gradually been incompetent for this task. A method based on μ-analysis techniques was used to solve this very difficult problem. The aircraft model and flight control law used in the prese nt study is a twin-engine fighter with a robust inverse dynamics estimatio n(RIDE) controller. Our approach was applied to evaluate a linear stability margi n criterion currently widely used by the aerospace industry. Using the linear fr actio nal transformation based uncertainty model developed from the nonlinear aircraft model, and a fictitious multiplicative input uncertainty representation of the criterion, stability robustness analysis results were presented for the flight co ntrol law. Compared with traditional grid-based ones, the μ-analysis based met ho d has two obvious advantages which provide more rigorous and efficient in the pr esence of multiple sources of parametric uncertainty. One is the points between grids can be cleared, the other is there exists no "disaster of dimension" pro blems.