It refers to the fact that when purchasing a certain commodity or service, three or more people form a group-buying group and can enjoy a more favorable price than purchasing individually. The group buy price will be lower than the price of individual purchase, merchants can attract more consumers through the group buy way, increase sales and popularity, so as to reduce the cost of a single consumer. Group-buy price is often found in the catering, tourism, entertainment and other service industries, is a kind of promotional marketing tools. With the development of group-buying mode, three-person group-buying price is no longer the only group-buying method, there are also two-person group-buying price, four-person group-buying price, five-person group-buying price and other different forms of group-buying methods. In addition, the group-buying industry is also facing a number of problems, such as false advertising, substandard service quality and other issues, so in the group buying need to choose a formal, reputable group-buying sites or merchants, to avoid fraud and losses by unscrupulous merchants.