Particulate matter (PM) exposure, especially PM2.5 and its components, is a well-known cause of mortality. The purpose of this review was to investigate the associations of long-term exposure to PM2.5 and its components with mortality from all-cause, cardiovascular, respiratory, and ischemic heart using cohort studies. A systematic review of literature was achieved on databases of Medline/PubMed, Scopus, and ISI Web of Science. A random-effect meta-anal. was applied to compute the pooled hazard ratio (HR) with 95% confidence interval (CI). Heterogeneity of studies and the risk of bias for all selected studies were also evaluated. We found a 5% (95% CI 3%-6%) increment in all-cause, a 10% (95% CI 5%-14%) increment in cardiovascular, a 1% (95% CI -1%-4%) increment in respiratory, and a 10% (95% CI 2-17%) increase in ischemic heart mortality per interquartile range (IQR) increase in PM2.5 concentration As for PM2.5 constituents, the strongest all-cause mortality was found for K+ (23%, 95% CI 2%-44%), NH+4 (15%, 95% CI 8%-22%), SO2-4 (9%, 95% CI4%-15%), BC (6%, 95% CI 4%-9%), and NO-3 (3%, 95% CI 1%-5%). Similar associations were found for cardiovascular, respiratory, and ischemic heart mortality. Our study provides clear evidence that long-term exposure to ambient PM2.5 and its chem. constituents (especially K+, NH+4, BC, SO2-4 and NO-3) increased mortality risk.PROSPERO CRD42022353365.