Abstract: With the “in-phase” and the “out-of-phase” derivatives of the aerodynamic coefficient for pitching and yawing motion of a delta wing, the state space models based on two-step linear regression method are established. The accuracy of the model are also compared and verified with the experimental data. It shows that the established models can describe the nonlinear and unsteady aerodynamic characteristics of a delta wing at high angles of attack. The relative simple models which are based on the physical meaning of the actual flow contain more nonlinear characteristics. In addition, wind tunnel small amplitude dynamic test data of the plane model are acquired to estimate parameters of the state-space model. It shows that the result of the state-space model is consistent with and the experiment data and most of the data are coincidence basically. However, there are some differences between them. Therefore, the establishment of the state-space model for a specific plane still needs to discuss further.