To depict,understand,evaluate,predict,control,manage or enhance software-related artifacts,researchers and practitioners often rely on empirical methods.Empirical methods have been widely used in software engineering,and they are attracting increasing attention over the years.By conducting a systematic mapping,this paper aims to provide a literature survey of 250 papers published in a typical journal-Empirical Software Engineering,from January 2013 to June 2017.With qualitative and quantitative analysis,this survey reveals the commonly used empirical research methods,research purposes,and the application of the methods in subfields of software engineering,including the solved problems and some new features.The findings also cover the use of open source projects,data source,data collection methods and commonly used mathematical statistics methods.Finally,this paper illustrates validity threats and discusses the future work,opportunity and some open issues of empirical research in the era of big data.