中文摘要：

从2003-2004年沪深两市具有代表性的81起公司收购兼并活动来看，并购总体绩效在短期内会得到改善，但长期来看，公司并购并没有带来经营效率的提高。对于收购公司来说，上市公司并购当年绩效有较大提高，随后绩效下降，甚至抵消了之前的绩效提高，并购没有实质性提高并购公司的经营绩效；对于目标公司来说，并购当期会使绩效下降，并购以后公司绩效上升，公司并购使得效率提高。

英文摘要：

Using 81 samples of merger and acquisition （M＆A） events in Shenzhen and Shanghai stock markets in 2003 and 2004, we selected 10 financial indicators and did an empirical research on the variations of performance of Chinese listed companies after M＆A activities. Meaningful results were obtained from the research as followed. From the output of overall samples, the performance of M＆A was definitely improved in short term, but it was not an efficiency promotion in the long term. As far as acquiring firms which were concerned, performance grew dramatically in the same year of M＆A actions, and then followed by a decline even to the extent that reduction offset the previous modification. So it is sagacious to reach the conclusion that M＆A will not arouse substantial increase to the companies＇ operating performance. As far as target firms that were concerned, performance will ascend gradually in the wake of a drop on the spot. M＆A leads a positive role in efficiency.