Abstract: The Beijing-Tianjin-Hebei and its surrounding areas (Beijing-Tianjin-Hebei Region) are one of the most representative urban agglomerations in China with heavy air pollution, especially the ambient PM_2.5 pollution. In order to estimate the disease burden of PM_2.5 in the Beijing-Tianjin-Hebei Region '2+26' cities and explore the health benefits of future air quality improvement, this study estimated the numbers of PM_2.5-related excess deaths in 2015, and in 2025, 2030 and 2035 under the '14th Five-Year' and Medium & Long-Term PM_2.5 control targets in this region, using the classical method of disease burden assessment of environmental factors. The health benefits of PM_2.5-control targets were estimated based on the above results. The results show that the number of excess deaths caused by PM_2.5 in the Beijing-Tianjin-Hebei Region '2+26' cities in 2015 was 15.11×10⁴. If the air quality improvements fully achieve the '14th Five-Year' and Medium & Long-Term PM_2.5 control targets, the PM_2.5-related excess deaths in the Beijing-Tianjin-Hebei Region '2+26' cities will be 11.49×10⁴, 10.62×10⁴ and 9.85×10⁴ in 2025, 2030 and 2035, respectively, which are 23.96%, 29.72% and 34.79% less than 2015. The comparison between age groups shows that the proportion of PM_2.5-related excess deaths in the old groups (aged 65 or more) is much higher than in the young groups. The disease-specific comparison shows that the PM_2.5-related excess deaths from cardiovascular and cerebrovascular diseases (in this study: stroke and ischemic heart disease) have the largest proportion among the total excess deaths and presents increasing trends in future. Our research shows that the future air quality improvement in the Beijing-Tianjin-Hebei Region '2+26' cities will significantly reduce the PM_2.5-related disease burden and bring significant health benefits. However, due to the impact of population growth and aging, the overall PM_2.5-related disease burden will remain heavy in the future. China should continuously promote the prevention and control of air pollution in the Beijing-Tianjin-Hebei Region and at the same time, pay attention to the health protection of vulnerable population groups such as the elderly and the people with chronic diseases, especially those with cardiovascular and cerebrovascular diseases, so as to further reduce the burden of PM_2.5-related diseases.