Abstract: Classical linear flutter analysis is based on the solution of flutter eigenvalue problem, and needs to track the root loci to determine the correct flutter boundary but sometimes may fail. To solve this problem, a new flutter solution called μ-ω method is presented by utilizing modern robust control theory. Based on the frequency-domain μ analysis, this method is established by applying dynamic pressure perturbation to the flutter equation with frequency domain unsteady aerodynamics. It is found that the continuity of the real μ analysis is crucial to this method, so a two dimensional wing model with steady aerodynamics is adopted to explore the continuity of real μ analysis. It is proven that the μ value obtained by real μ analysis is not a continuous function of frequency, but if complex perturbation is introduced, the complex μ analysis does guarantee the continuity of μ analysis. According to this conclusion, the algorithm of the μ-ω method is extended with complex μ analysis. Numerical results demonstrate that the complex perturbation μ-ω method is a useful frequency domain flutter solution with good convergence and accuracy.