A fully implicit tightly coupled numerical method is developed for the limit cycle flutter of the wing. The Roe scheme and dual time stepped method are adoptedin the spatial and time discretization of flow field, respectively. The Newmark method based on the finite element method is adopted in the structural transient response. The geometrical nonlinearity of the wing under the large deformation is also considered, and the implicit time marching scheme is used in theanalyses of flow field and structure.On the basis of the traditional loosely coupled method, the pseudoiteration is added in the tightly coupled method.When the pseudo-iteration converges, the physical iteration related to the real time step is sequentially analyzed, which can reduce the time lag effect caused by the frozen boundary conditions in the analysis of traditional loosely coupled method.The transonic limit cycle flutter of the cropped delta wing is also analyzed. The results show that the limit cycle flutter amplitude and the frequency of wing tip obtained by the tightly coupled method are better than the traditional loosely coupled method,closer to the test results.Therefore, the tightly coupled method can eliminate the accumulated errors inthe time marching and has a higher coupled time precision.