Abstract: In order to study the spatial distribution of buffeting drag on bluff bodies and the mechanism of flow-structure interaction, the span-wise correlation and the energy distribution of buffeting drag on stationary rectangular cylinder with side ratio B/D=2 were investigated by synchronically surface pressure measurement. The results show that the buffeting drag is more correlated than the longitudinal turbulent component when oncoming flow approaches the windward side of the cylinder, which may be accounted for the stretch of the vortices in the turbulence along the span. Meanwhile, the vortices will be distorted at separation point. The large scale coherent vortices are contaminated by small eddies, which would attenuate the span-wise correlation of the fluctuating pressures. In addition, the energy will be transferred from lower frequency to higher frequency when the longitudinal large scale vortices break into smaller eddies at the separation point. The experiments also indicate that the fluctuating pressures on the leeward side are mainly determined by the signature turbulence generated by the bluff body. It is inferred that the shedding vortices on the leeward side are stretched larger than the ones on the windward side along the span, which may causes larger span-wise correlation of surface pressures on the leeward side. Contrary to the longitudinal energy transition pattern, small scale eddies with higher frequency are possibly not stretched longitudinally but dissipated when the separation bubble moves from the separation point to mid part of the leeward side. Thus, the spectra of fluctuating pressures keep constant at lower frequency and decrease at higher frequency.