This article assesses cumulative average abnormal returns and cumulative abnormal returns of 110 A-share listed companies which have operated overseas mergers and acquisitions since 2000 based on CAPM model. For the overseas M&A before the financial crisis and during the crisis, we find that the former increases the company's shareholder wealth, while the latter reduces the shareholders' wealth. The target companies of M&A has gradually transformed from the manufacturing sector accounted for the majority into the diversity. The M&A performance of manufacturing enterprises in the financial crisis is much higher than the one during the financial crisis, but financial service companies and resource companies have a unique characteristics in M & A performance. Finally, investors' confidence is frustrated by the crisis, which makes them response weak on overseas M&A activity.