To address issues such as poor visual guidance, narrow field of view, and short sight distance during nighttime driving on mountain roads, this study proposed a visual space enhancement evaluation method applicable to mountainous roads at night. By integrating active and passive traffic safety facilities, a visual space enhancement strategy adapted to the nighttime environment of mountain roads was proposed. A multidimensional evaluation indicator for visual space was established based on co-simulation. The effectiveness of the strategy was verified from the perspectives of visual space expansion and driving safety improvement by taking a trunk highway in the Qinling mountainous region as a case study. The results show that the proposed visual space enhancement measures can significantly increase effective sight distance and improve driving safety, especially on high-risk road sections such as complex curves and steep longitudinal slopes, where they can effectively reduce the risk of traffic accidents.