This thesis tries to analyze the performance towards those Chinese A share public companies that carried out different ways of M&A----that is horizontal, vertical and conglomerate M&As. It depicts the data of 2009-2015 M&A events, analyzing the stock price performance of the acquiring companies in the same year, the following 3 years and 10 years or up until end of 2019 year. This thesis also analyzes the financial performance of the acquiring companies in the same year, from 3 years perspective and 10 years perspective, to draw the conclusion that horizontal mergers show obvious performance increase compared with vertical and conglomerate M&As. Finally, the thesis uses the case of Aier Eye Hospital to illustrate that horizontal M&A can create value by adopting a united supply chain, replicable management mode, an integrated human resources management, training and incentive system and wide brand recognition.