Abstract: Due to the special structure and aerodynamic configuration, the flutter characteristic analysis of T-tail empennage is complicated and the flutter speed is influenced by flight condition and some parameters that had been omitted, e.g. stabilizer dihedral. To solve these problems, the influence of the dihedral of horizontal- stabilizer, the steady lift on horizontal-stabilizer and oscillatory modality on T-tail flutter are analyzed. The special additive unsteady aerodynamic using in T-tail flutter is investigated especially, and it is been established that the analytic approach of unsteady aerodynamic and flutter for T-tail. In order to validate analytic method, the experimentation of reduced scale T-tail model was carried out in the low speed wind tunnel. According the result, the special aerodynamic of T-tail affects mainly the form of bend-torsion coupling of fin. The flutter speed descends with attack angle increasing of stabilizer, and it can improve the flutter speed by using the negative dihedral in design. According the theoretical analysis of test result, the mechanism of T-tail effect is explained and some suggestion is given for practical design.