Abstract: Purchase of Service Contracting (POSC) is a new way of functional transformation and public service supply of the government. This paper examines the regulation mechanism of POSC based on the comparative research. The findings reveal that POSC in China is rapidly developing in terms of public policy and practice, at the same time, there is a lack of comprehensive consideration of purchasing assessment and supervision. The key point of the article is that in order to promote the effective development of the government POSC, it is urgent to strengthen the construction of regulation mechanism. Specifically make clear the main body and operation mechanism of evaluation and supervision, and the establishment of multi-agency system, to strengthen the process of regulation and improve the assessment mechanism.