How to create a fair and competitive business environment for enterprises is a major challenge faced by China’s deep-seated reform and further development. Since the Eighteenth National Party Congress, the country’s top leadership group has taken the rectification of officialdom and market ethos as an important means of comprehensively deepening reforms. Through a series of " cracking down on both tigers and flies” anti-corruption actions, several degenerate officials have been investigated and the campaign wins wide public praise. However, the impact of the " cracking down on both tigers and flies” campaign on micro-business operations and macro-economic development of enterprises has not yet reached a consensus. In view of this, by taking China’s A-share listed companies as a sample, we use the event study method to examine the impact of the anti-corruption campaign on the company’s value and attempt to provide evidence for the impact of clean government construction from the perspective of financial markets and investors. We find that during the investigation of degenerate officials, the stock price of listed companies in their jurisdictions has a positive market reaction, indicating that investors believe that the construction of a clean government can effectively curb corruption, purify the regional business environment, and thus reduce the company’s operating cost and enhance the company’s value. Furthermore, we also find that when degenerate officials are investigated: （1） the share price of enterprises which located in the area with lower institutionalized government administration has more positive market reaction; （2） state-owned enterprises have significantly higher cumulative excess return rate than non-state-owned enterprises; （3） the higher the level of officials is, the higher the cumulative excess return rate of the company’s stock price in its jurisdiction is, that is, the " tiger” has a more positive effect on the business environment rectification; （4） when officials take office in their hometown, the market reaction of the company’s stock price in its jurisdiction is relatively better: this further indicates that investors believe that the investigation of corrupt officials can effectively curb corruption and purify the regional business environment; （5） in the long run, investors reverse their view of " cracking down on both tigers and flies” and believe that high-pressure anti-corruption will also have a negative effect. Overall, the results of this paper indicate that investors believe that the " cracking down on both tigers and flies” campaign can create a fair and competitive market environment, which can improve the company’s operation efficiency, thereby enhancing the company’s value, but it may also bring disadvantages in the long run, requiring institutional development while carrying out anti-corruption. In terms of theoretical significance, this paper enriches the literature on corruption and economic growth, proving that when the formal institution is valid, corruption serves the role of " hand of plunder” and hinders economic growth; while in the case that the formal institution is invalid, corruption acts as the " hand of support” and can play the role of lubricant. In terms of practical significance, we not only provide evidence for the necessity of anti-corruption, but also provide a reference for how to further improve the effect of building a clean government. What’s more, we also provide evidence for the necessity of building state governance capacity and deepening the reform of the administrative system.