According to the investigation of several roads in Inner Mongolia Autonomous Region， it is found that the sections with collision guardrails have serious snow hazards. Due to the limit of many factors such as snowfall， winds， time and research period， it is difficult to monitor the snow drift on site. Therefore， the computer simulation “digital wind tunnel” is used to select the typical embankment section form in the separated subgrade， establish the subgrade model and collision guardrail model， and quantitatively analyze the characteristics and influence relationship of different collision guardrail setting parameters on the wind speed and flow field of highway section. Through the analysis of the data of the pavement wind speed control points and the overall wind speed cloud map of the pavement， the irregularity of the shape of the anti-collision guardrail hinders the flow of wind-blown snow， resulting in a significant reduction in the pavement wind speed， causing a large number of snow particles to deposit on the pavement， resulting in road snow. Therefore， in areas with frequent wind-blown snow， the separated subgrade section may slow down the slope gradient or use cable guardrail to ensure the safety of the roadside and eliminate or reduce the occurrence of snow damage. Therefore， this paper can provide theoretical basis and reference for the design and maintenance of roadside collision guardrail of highway separated subgrade in snowy areas.