The vortex shedding response of a box bridge girder deck with and without railings had been investigated by wind tunnel experiments with the objective of identifying the mode of vortex excitation and effects of railings on vortex-induced vibration of bridge deck. Tests on 2 spring suspended models (deck with railings and bare deck) reveals this situation. Measurement of the fluctuating pressure around the deck surface indicates that vortices shed from the downstream section with railings have greatly contributed to the vertical vortex-induced vibration, while the bare section pressure fluctuations over the entire upper and lower surface have little contribution to the vortex response. The presence of railings does not change the mean pressure distribution of soffit plate, but significantly change the pressure distribution on the upper surface. When introducing the railings it is noted that the fluctuating pressures on the entire lower surface and the downstream of upper surface are markedly increased.