Abstract: Section model wind tunnel test is one kind of effective method to estimate vortex-induced vibration (VIV) response of long span bridge girder.The large-scale (usually from 1:15 to 1:20) section model has larger geometry scale.And the Reynolds number of large-scale section model wind tunnel test is close to that of prototype.Moreover,the geometry detail could be simulated more accurately by the large-scale section model.A large scale(1:20) section model of one flat steel box bridge girder was tested to get accurate VIV response and the optimized position of check vehicle rail.And several characteristics of VIV were discussed in detail such as VIV amplitude vs.damping ratio or Scruton number,VIV wind speed range vs.damping ratio or Sc,wind attack angle vs.Strouhal number,double vertical VIV phenomenon and so on.Theoretic and experimental foundation is provided here to expand the section model test result to prototype.