Abstract: The object of modern social science has features of continuity and linearity. But there are few research on sudden event, but they are dynamics of social development. Both the path dependence or obstacle of development will be broken by a sudden event, and the opportunity windows will be opened. Failure in system will be exposed by sudden event, which will guide the direction of institutional change and technical progress. In public policy and public management the applying of vulnerability, chaos and event-institution change theory will be useful to push institution and technical progress.