Abstract: In this paper, three jobs were carried out about theunsteady dynamic aerodynamic effects during the sliding skin swept-anglewing morphing under the incompressible condition. (1) The wind tunnelexperimental measure technologies about the unsteady dynamic aerodynamiccharacteristic during aircraft morphing were studied; (2) The aerodynamichysteresis effects during the swept-angle morphing were investigated and themechanisms were analyzed initially; (3) The unsteady dynamic aerodynamiclinear models were made during morphing based on the experimental results.The primary research indicated that: (1) the method of the forced periodicmorphing could obtain the unsteady dynamic aerodynamic hysteresis effectseffectively; (2) there were two mechanisms which bring the effects: ``Themoving boundary effect'' and ``The flow structure hysteresis effect''. Andthe hysteresis effects in this paper might be caused by the latter mainly;(3) the dynamic derivatives of the lift and pitching moment coefficients tothe morphing rate of swept-angle were defined in this paper, which can makethe linear model about the unsteady dynamic aerodynamics during morphing.