蒙古国色楞格河是世界最大的淡水湖——贝加尔湖最重要的入湖河流，该流域的生态安全事关蒙古高原和中国北方生态屏障建设。为了明晰色楞格河流域的生态安全状态，本文提出基于压力-状态-响应（Pressure-State-Response，简称PSR）模型的评估方法和技术流程，以期通过评估应用为本区域可持续生态环境管理提供参考。首先对色楞格河流域土地覆盖进行分类，结合蒙古国官方统计数据，分析色楞格河流域生态环境现状。进而基于PSR模型，采用层次分析法，对色楞格河流域生态安全现状进行评估。结果表明：色楞格河流域内典型草地所占的面积最大约为16万km²，占总面积的53%，其次为森林，面积约为10km²，占总面积的32%，植被覆盖度较高。流域内生态环境响应以及生态环境状态都处于较安全等级，其中耕地面积及农业机械化水平对生态环境状态和生态环境响应的影响较大。但同时，存在着较大的生态环境压力，土地退化面积及牲畜存栏量是造成生态环境压力较大的主要影响因子，未来应加强这两方面的政策调控。总体而言，蒙古国色楞格河流域的生态安全处于较安全等级，可适度进行开发利用。

The Selenge River in Mongolia is the world's largest freshwater lake—Lake Baikal, the most important inlet river, and the ecological security of the basin is a matter of concern for the construction of the ecological barrier on the Mongolian Plateau and in northern China. In order to clarify the ecological safety status of the Selenge River basin, this paper proposes an assessment method and technical process based on the Pressure-State-Response (PSR) model, with a view to providing a reference for sustainable ecological management in the region through assessment applications. Firstly, we classify the land cover of Selenge River Basin and analyze the ecological status of Selenge River Basin with the official statistics of Mongolia. Further, based on the PSR model, a hierarchical analysis was used to assess the ecological safety status of the Selenge River basin. The results show that the real steppe within the Selenge River basin occupies the largest area of about 160,000 km², accounting for 53% of the total area, followed by the forest with an area of about 10 km², accounting for 32% of the total area, with a high vegetation cover. The ecological response and ecological state in the watershed are at a safer level, where the arable land area and the level of agricultural mechanization have a greater impact on the ecological state and ecological response. However, at the same time, there is a greater ecological pressure, and the area of land degradation and the stock of livestock are the main influencing factors that cause greater ecological pressure. In the future, policy regulation in these two aspects should be strengthened. In general, the ecological safety of the Selenge River Basin in Mongolia is at a relatively safe level and can be exploited moderately.