People's Republic of China Public Library Law has clarified the way of social forces participate in public libraries construction, establishes the implementation system of government purchasing public library services, donors' titles, tax preferences, and stipulates the penalty measures when social forces violate the regulations in developing public libraries. Taking the Jiading district public library of Shanghai municipality as an example, this paper systematically analyses the specific ways, practical experience and development direction of social forces participating in public libraries construction, hopes to optimize the ways of social forces participating in the public libraries construction, effectively allocate service resources, improve service efficiency.