Abstract: Ostrom Elinor started her polycentric journey trying to challenge the state theory and the market theory. She proposed the polycentric theory of urban governance using the public economics theory through the empirical research of police services lasting for 15 years in her early stage. Later she developed the institutional analysis and development framework (IAD), which was the basis for empirical research of common-pool resources, including fishery, forests, irrigation, and water basin for more than 30 years. With this process, she discovered the eight design principles of self-governance. Now her latest theoretical inquiry includes the following four aspects: further explore a more general theory of behavior approach to human rational choice; play the central role of trust in research; further consider the micro-situational context of human collective action; develop the general framework for the sustainability of social-ecology system pushing the frontier of collective theory and common-pool resources. Inter-disciplines, multiple methods, and collaborative researches are the most characteristics of her research.