The urbanization process has increased the pressure of urban public service supply in Henan，and the differentiation，diversification and individualization of residents’ needs have overwhelmed the government. How to further improve the supply level of public services in Henan cities and meet the needs of residents has become an important part of building a service-oriented government. By constructing a feedback model of public service supply，this paper analyzes the binary subject of public service supply process in Henan cities and finds that the constraints of public service supply in Henan cities in the feedback chain of public service purchase，direct public service supply and indirect public service supply make the public service supply in Henan province unable to form positive feedback incentive effect in the whole chain，which limits the public service supply This paper focuses on the constraints. Based on these constraints，this paper proposes measures to improve the level of public service supply in Henan cities in order to build a positive feedback incentive mechanism for public service supply，enhance the sustainability of public service supply，and continuously improve the level of public service supply.