Meta-analysis is a statistical technique for summarizing previous quantitative research with its unique advantages.In this article we gave a brief introduction about the concept, steps about meta-analysis.And also illustrated several examples including cardiovascular events caused by TZDs, the incidence of adverse drug reactions(ADR) in hospitalized patients and ethnic differences in risks of adverse reactions.In addition, we also suggested that sensitive analysis, sub-group analysis and model selection should not be ignored while applying Meta-analysis in ADR signal detection.