As a new field, the two-sided platform has multiple dilemmas and contradictions in the governance of intellectual assets within the platform, which cannot be solved by the appropriability theory. It is urgent to introduce a new theoretical perspective to explain how innovators profit from innovation in the context of the two-sided platform. It is possible to explain the governance practice of intellectual assets in the two-sided platform by institutional work which observieshow specific behaviors construct the institutional workfrom the micro level, and the legitimacy theory whichanalyzesthe interactions between organizations and the environment. Institutional work is the institutional construction in the process of micro-action from the perspective of "work". Legitimacy theory is a larger conceptual category than appropriability theory, which can construct regulations, norms and cognition that benefit from innovation by observing the practical actions of intellectual assets governance on the two-sided platform. Through the vertical single case study method based on the grounded theory, the practice of intellectual assets governance on the two-sided platform is presented as a three-stage institution change model of institutioncreation, institution reengineering and institution maintenance. At the stage of institution creation, the establishing contracts work for intellectual assets governance is carried out. Platform leaders, buyers and rights holders, as the main actors in the institutional work, jointly carry out legitimation strategies based on symbolic strategies and construct "cognitive legitimacy" and "normative legitimacy" in the field of intellectual assets governance organization. However, the "norm" and "cognition" at this stage have produced deviations in the pursuit of the network effect on the two-sided platform, resulting in the failure of effective governance in establishing contracts work and pushing the governance of intellectual assets to the next stage. The stage of institution reengineering includes building identity work and establishing connectionworkofintellectual assets governance.Platform leaders, rights holders, authoritative departments and small and medium-size sellers have become the majoractors in the implementation of the institution. Through symbolic legitimation strategiesand material legitimation strategies, the organization field of intellectual asset governance in the two-sided platform has been constructed to form regulative, normative and cognitive legitimacy and achieve the goal of intellectual assets governance. In the institution maintenance stage, the guaranteeing and facilitating work of intellectual assets governance was carried out. Through the joint actions of platform leaders, rights holders, local governments and small and medium-size enterprises, the intellectual assets governance institution constructed in the institution reconstruction stage was strengthened and promoted, and the cognitive legitimacy and regulative legitimacy were constructed in a wider organization field, ultimately realizing intellectual assets governance. The institution change model of intellectual assets governance expands the theoretical boundary of profit from innovation, explains the logic of intellectual assets governance on the two-sided platform with legitimacy theory, and deconstructs the actors, the legitimation strategies, the legitimacy in the organizational field of intellectual assets governance, the manifestation of institutional workstep by stepand reveals the logical relationship between them. The analysis of intellectual assets governance institutional work enriches the connotation of institutional work. The establishing contracts work, buildingidentity work, establishing connection work, guaranteeing and facilitating workof intellectual assets governance have expanded the connotation of institutional work and revealed the interrelation between different institutional works. The research on symbolic legitimation strategies and material legitimation strategies respond to the current change in the research on legitimation strategies: the legitimation strategies should be realized by the substantial change in the material world and the change in symbols and languages.