After the development over the past five decades，two main research traditions have shaped in the American Social Science Research on Hazard：the sociological tradition and the human geographical one. Based on the methods of literature review，personal interview，and non-participant observation，this paper investigates the Natural Hazards Center at Colorado University-Boulder，a typical and leading institution of the human geographical tradition. Firstly，the notion of human ecology reflects the philosophical background of pragmatism in American hazard research. Secondly，four dimensions of institutionalization studies，that is，shared value，institutional arrangement，organizational design and physical basis，apply to the systematic analysis of Natural Hazards Center，including its establishment，mission，evolution and impact. Finally，it critically examines the research field of American social science research on hazard，according the perspective of ‘Post-normal Science’.