Child protection service is a combination of intervention, services and care. In practice, Taiwan’s local governments make use of the public-private partnership model to include more manpower and resources from the private sector for providing better service. The author discusses issues regarding cooperation and supervision of outsourcing child protection service, focusing on the family-based intervention plan. Based on theoretical analysis and the results of interview with social workers in both private and administrative agencies, this thesis suggests that child protection service outsourcing should be considered as “professional involvement.”, and the “Child and Youth Family-Based Intervention Program Contract” as administrative contract. For public service outsourcing, cooperation and supervision are equally important. However, governmental supervision seems to be easier said than done, especially when the manpower and resources provided by the private agencies are critical to the network of child protection service. To strike a balance between cooperation and supervision, this thesis advocates that the contract between public and private agencies should include provisions addressing terms and conditions of government supervision.