Ice falling from bridge tower beams in winter is one of the major hidden dangers threatening bridge traffic safety. Systematic analysis of the mechanism of beam icing disasters in adverse meteorological microenvironments is an urgent need to ensure bridge traffic safety. Based on FLUENT and FENSAP-ICE software, a numerical simulation model of ice accretion for bridge tower beam was proposed. The effects of micro meteorological parameters such as wind speed, liquid water content and ambient temperature on the evolution process of icing disaster were discussed. Results show that the proposed method has high feasibility and accuracy under both clear ice and frost ice conditions. The numerical simulation of ice accretion of the Second Wuhan Yangtze River Bridge shows that the icing area is concentrated on the leading edge and upper and lower edges of the windward side of the beam, showing a "U" shaped distribution characteristics, which is the key area for anti-icing and de-icing of the beam. The adverse meteorological microenvironment considerably affect the form, distribution and amount of icing on the crossbeam. The ice accretion is greatly affected by wind speed and liquid water content, but is less affected by temperature.