Abstract: Aerodynamic force is the basis of wind resistance calculation and vibration analysis of long-span bridges. The change of aerodynamic force with the Reynolds number of streamlined bridge sections is a concern of wind engineering research and bridge design. Through a wind tunnel test, the law of surface wind pressure distribution with the Reynolds number is studied. The mechanism of the Reynolds number effect was analyzed. The variation of the wind pressure distribution with the Reynolds number on the surface of the model is obtained through a rigid segment model pressure wind tunnel test. Through the characteristic orthogonal decomposition method based on the power spectral density matrix, the fluctuating pressure field of the structure surface is analyzed in the frequency domain. The main distribution pattern and frequency of the fluctuating wind load on the streamlined bridge section are analyzed. The effect of the Reynolds number on the fluctuating pressure field of the structure is also analyzed. It is found that the action of fluctuating wind load on the surface of a streamlined bridge changes with the Reynolds number, and that the flow separation and repayment at a specific position change with the Reynolds number and affect the overall aerodynamic force and the vortex shedding law.