Abstract: An airship is used for high resolution earth observations in near space. The study of mechanical properties is important. An airship is made of flexible material, and it is prone to large deformation under the aerodynamic forces. The fluid-structure interaction effects should be considered. Loosely coupled method is adopted. An airship model was calculated to obtain the flow field and the structure distribution characteristics. The simulation results are verified by the experimental data. Results show that: the effect of fluid-structure interactions is not needed to consider for a rigid airship. For a semi-rigid airship, the rubber part is the main region affected by the coupling. The displacement is enlarged 5%. For a soft airship, the tail and head of the airship have the most obvious deformation. The maximum displacement increment is 225%. Moreover,the control parameters of airship deformation are attained by the dimensional analysis. The influences of the elasticity modulus, internal pressure, and flow condition are discussed. The deformation will satisfy the geometrical similarity law when the model meet the geometric, material, and dynamic similarity with the test model.