Government purchasing services has become a useful way to observe the relationship between the government and social organizations. And strategies of social organizations to safeguard their interests are increasingly concerned. The “institution-technology” environment of government purchasing services offers social organizations some spaces for developing. The government-owned and non-government-owned social organizations relying on organizational attributes and resources adopt different organizational strategies in order to undertake government purchasing services and obtain favorable positions in the situation with governmental purchasing. Government-owned social organizations rely on the strong support of government，get the legitimacy and resources of the institution，and exhibit the following strategies：institutionalized structure，network alliance，innovation within the system，project management. And these strategies can be called the predetermined action. Non-government-owned social organizations adjust their strategies to the specific environment in order to obtain the key resources for the survival and development. They exhibit the following strategies：resource-oriented action，social mobilization，administrative embededdness，business-oriented ideas，and professional orientation. And these strategies can be called induced action. Social organizations’ strategies are important mechanisms to balance favorable and unfavorable factors in government purchasing environment.