Abstract: Equivalent static wind load (ESWL) is a general method in engineering design. Wind-gravity coupling effect (WGCE) refers to gravity second order effect of structure caused by wind load. Mean square deviation of restoring force of structure can be taken as ESWL of fluctuating wind load by equivalence of restoring force and formula about distributed load along buildings is concluded in the paper. The results show that formula contains additional item about gravity which is not listed in general expression. ESWL expression for structure is obtained by adding partial factors to each item. Vibration factor including WGCE is different from that is presented in the load code of PRC. WGCE makes vibration factor distributed along buildings decreasing in the middle and lower parts and increasing on the upper part. Gravity-rigidity ratio has strong influence on WGCE, while other factors have little influence.