Abstract: Inaccuracies of the axial stiffness and internal force distribution of the bridge girder in aero-elastic full bridge models were studied by using the finite element method, and their influences on aerostatic responses of long-span cable-stayed bridges were examined. It is found that the inaccuracy of the axial stiffness and the inaccuracy of the internal force distribution can lead to significant underestimation of the aerostatic responses of the structure, but their effects can be counteractive and therefore offset the deviation from each other. When the two inaccuracies are involved simultaneously, the wind tunnel tests will underestimate the aerostatic responses of the bridge girder of about 10% in the vertical direction and 3% in the lateral and torsional directions. Since the aerostatic instability of cable-stayed bridges mainly presents as torsional divergence of the bridge girder, wind tunnel tests based on aero-elastic full bridge models are of acceptable accuracy for the aerostatic responses of long-span cable-stayed bridges.