Abstract Background Research in the USA and in west European countries has shown that long-term exposure to fine particles (PM2.5) is associated with an increased risk of mortality from cardiovascular disease, but no such studies have been done in China to date. We have estimated the association between long-term exposure to PM2·5 and cardiovascular mortality from cardiovascular disease in a cohort of Chinese men. Methods For this prospective cohort study, we monitored men aged 40–79 years from 44 counties or cities in China since 1990–91. Annual average PM2·5 levels for the years 2000 and 2005 were estimated for each of the 44 cohort locations using a combination of satellite-based estimates, chemical transport models, and ground-level measurements developed for the Global Burden of Disease study. We used a Cox proportionate hazards regression model to estimate hazard ratios (HR) for cardiovascular mortality during 15 years of follow-up, adjusting for age, urbanicity (ie, urban vs rural), smoking status, alcohol consumption, and body-mass index (BMI). This study was approved by the ethics committee of Chinese Center for Disease Control and Prevention. Findings 186 399 men were included in the cohort. 52 000 deaths were reported during the 15 years of follow-up, of which 18 773 (36%) were due to cardiovascular disease, which included 3726 deaths from ischaemic heart disease, 6765 deaths from haemorrhagic stroke, and 2688 deaths from ischaemic stroke. The mean PM2·5 concentration between year 2000 and 2005 was 43·7 μg/m3 and ranged from 4·2 μg/m3 to 83·8 μg/m3 . An increase in PM2·5 of 10 μg/m3 was associated with a 9·7% increase in the risk of mortality from ischaemic heart disease (HR 1·097, 95% CI 1·079–1·116), a 4·4% increase in the risk of mortality from haemorrhagic stroke (HR 1·044, 95% CI 1·031–1·057), and a 13·5% increase in the risk of mortality from ischaemic stroke (HR 1·135, 95% CI 1·113–1·158). Interpretation This study estimated cardiovascular mortality risk associated with exposure to ambient PM2·5 over a broader range than in previous studies, including the high levels currently observed in China and other low-income and middle-income countries. Long-term exposure to PM2·5 was associated with cause-specific cardiovascular mortality in Chinese men. Relative risks were comparable to those reported in studies in high-income Western countries. As limitations of the study, we only included men in our cohort, and we were not able to assess the effect of within-city air pollution contrasts on mortality because personal exposure measurements were not available during the period of follow-up. Funding This study was supported by the National Basic Research Program of China (“973 Program”, number 2012CB955500) and Gong-Yi Program of China Ministry of Environmental Protection (201402022).