In order to investigate the relationship between the intake of trans fatty acids and their serum levels and the risk of female breast cancer， we searched Pubmed， ISI Web of Science， ProQuest， Science Direct， CNKI， Wanfang， Weipu and other domestic and foreign databases. Literature selection， literature screening， data acquisition and quality assessment were conducted based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Meta analysis of the included studies was performed using Stata 16.0 software. Results: Trans fatty acid intake was not associated with breast cancer risk in women (combined effect size: 0.99； 95%CI: 0.92-1.06； I2=66.9%， P=0)； the intake of conjugated linoleic acid was positively related to the risk of breast cancer (combined effect size: 1.09， 95%CI: 1.02-1.16， I2=0， P=0.597). In addition， serum levels of trans fatty acids were not associated with breast cancer risk in women (combined effect size: 0.94， 95%CI: 0.47-1.42； I2=85.3%， P=0).