Abstract: Aerodynamic analysis is made for grid fin-body configurations in subsonic and supersonic flow. Vortex lattice formulation has been used in predicting the aerodynamic characteristics for grid fin in subsonic flow. An infinite line doublet and imaging vortices inside the body are employed to model body upward and wing-body carry over load.In supersonic flow, the grid fin is assumed to locate in the cross flow of the body, the wing panel theory is used for calculating the aerodynamic interfere factor of the grid fin produced by the body. The aerodynamic characteristics of some grid fin-body configurations have been calculated, the theory agreed quite well with the experimental data.