In recent years, information technologies have been developed extremely rapid and the development of IT such as Web2.0, smartphones, and cloud computing have not only brought a digital revolutionary impact on the production, life and the entertainment of people, but also stimulated the emergence of brand-new kind of business models as well as organization forms. The innovation activities of enterprises are no longer limited inside the enterprises or industries, moreover new technology and new concept continue to break through the boundaries of regions, organizations, and technologies. Cross-border, mix & match, and innovation ecosystem are becoming new models that lead different industries to integrate innovation and development. In particular, as the Internet is an open, sharing and distributed system, the cross-border integration and innovation among various participants has been taken for granted to lead to the emergence of a large number of new categories, such as mobile live streaming, AI medical robots, and driverless cars. Specifically, mobile live streaming becomes one of the most important ways to kill time confetti in less than two years like a storm. Therefore, this paper aims to figure out, as a new category, how mobile live streaming obtain legitimacy within the process from emergence to application, and to explore the process of obtaining legitimacy and the emergence mechanism of new categories. 

This paper takes Huajiao Live as an example to explore how a new category obtain legitimacy. The results show that legitimacy is an important resource for an organization to survive, maintain and develop. The acquisition of legitimacy is extremely important in the daily operation of an organization. As the label of a new organization, the emergence process of new categories is inseparable from the legitimacy acquisition process of the new organization. Most of the existing researches focus on how the mature companies can further improve the legitimacy of the organization, but few studies examine the legalization strategies adopted by new ventures from a vertical perspective, especially in the context of an unsound institutional environment. 

Through the longitudinal case study of the Huajiao Live, it is found that: First, the legitimacy acquisition process of new categories has obvious stages, and each stage focuses on different kinds of legitimacy. Specifically, new categories faces the lack of supervision at the initial stage of emergence. In the absence of external constraints, companies need to rely on ethics to self-discipline and obtain regulatory legitimacy. On the one hand, in the development stage, relevant regulatory rules are gradually improved, enterprises should continuously regulate the corporate behavior to behave in accordance with relevant laws and regulations to obtain regulatory legitimacy. And on the other hand, cooperating with appropriate companies to obtain normative legitimacy. Secondly, although there are different stages when enterprises obtain legitimacy, but regulatory legitimacy, normative legitimacy and cognitive legitimacy are equally important to enterprises. The lack of any kind of legitimacy will lead a huge impact on the development of enterprises. Finally, the acquisition of cognitive legitimacy runs through the entire process of acquiring the legitimacy of new categories. Enterprises should pay extremely high attention to cognitive legitimacy and implement appropriate strategies.