On the basis of scholars' review of correlation degree of mergers and acquisitions industry at home and abroad and positive study on M&A,this paper makes positive study on performance of M&A of listed companies in 2002,analyzes the influence of M&A on performance of the enterprises and reaches three conclusions such as emphasis laid on analysis and selection of entrance industry at the time of M&A,attention paid to integration management after M&A and reduction in governmental intervention.