Due to the high threshold requirements of applying for a large number of loans from banks, more and more small and medium-sized enterprises have chosen private placement to raise funds, and the betting agreements have been signed to protect the interests of both enterprises and investors. This paper analyzes the case that the bet agreement was applied by Mengniu Dairy and Morgan Stanley in private equity financing. It firstly expounds its background and financing process at that time, then explores why Mengniu Dairy can bet successfully. Finally, countermeasures and suggestions are put forward to promote success of the gambling agreement in private equity especially for small and medium-sized enterprises.