“Material Adverse Change Clause” (hereinafter referred to as MAC clause) refers to a clause arranged in the contract during the acquisition and merger of company in order to provide the buyer with an opportunity to terminate the transaction when the conditions of the target.MAC clause plays an essential role in international M&A. Almost all cross-border M&A agreements include MAC clause, and both parties often spend a lot of time negotiating and writing this clause. However, MAC clause writing is complicated in practice, and MAC clause content is often unsatisfactory. First, this paper analyzes the concept of MAC clause as the starting point, from its role and common types of MAC clause to explain. Secondly, based on the relevant data of MAC  clause in international M&A contracts in recent years, this paper analyzes the current situation of MAC clause use, especially the difference between the frustration system of use contract in the UK and the principle of change of use situation in China during the COVID-19 pandemic. Thirdly, starting from the case of LV's acquisition of Tiffany, this paper explains the use of MAC clause in actual cases and finds out the problems with its use. Finally, according to the above issues, this paper puts forward some suggestions for improving MAC clause and studies its development direction.