Policy practice is the pivotal path to construct public life for social workers. With recently prevalent government procurement of public services in China，social workers’ policy practice in non-profit social service organization has become an important proposition for the development of Chinese social work in the new era. According to the focus group study of social workers of A，a non-profit social service organization with youth in Shanghai，these social workers now have a certain understanding of policy practice，but their understandings remain incomplete and inexact. Social workers with youth hold the notion that their own influence on policy practice is quite limited，and their existing actions are still in a state of self-development，manifested as vocal advocacy practices based on consultation participation. The hierarchical relationship with the bureaucracy system not only sets the time-space structure over social workers to construct public life，but also provides resources and carriers for social workers in policy practice implementation. In this process，social workers with youth actively play the role of initiative，by means of the interaction，negotiation，or compromise with external structures，with the results of vocal advocacy. The interactive structure-agency framework provides implications on the role clarification and mechanism construction of social work in policy practice for future.