The longitudinal and lateral dynamic characteristics of the elastic missile are analyzed in this paper. The aerodynamic force and moment and structure mode are calculated. The unsteady aerodynamics additional caused by vibration is researched through simplified theory; the longitudinal and lateral rigid disturbance motion equations are established in term of the linear theory respectively. The elastic vibration dynamic response can be acquired after the unsteady aerodynamics loads additional are substituted to the disturbance motion equations as perturbation input. The outputs can provide raw data for stability analysis, precision analysis, control and guidance system design. The response of output shows that the longitudinal attitude angles and sideslip angle variation induced by elastic vibration will be very slight, but the variation of bank angle will be great, this result is matched with the experiment phenomenon.