Wind-gravity coupling effect(WGCE)is horizontal deformation that is caused by wind and enlarged by gravity. In order to analyze WGCE of extra-high building structure, the model of structure was established and derivation of dynamic equations was presented in the paper. WGCE coefficients of structure frequency, wind fluttering factor and response of structure were calculated and analyzed. The result shows that natural period of vibration becomes longer and wind vibration factor decreases as WGCE is taken into account in the calculation. WGCE will become evident if gravity-rigidity ratio, bending-shearing ratio and taper of tall building structure increase. It is suggested to take into account WGCE when calculating the structure of extra-high building with large gravity-rigidity ratio and complex sharp.