Firstly, this paper analyzes synergy connotation and realization mechanism between fiscal and financial service and the construction of new agricultural management system. Then, this paper analyzes reasons for why fiscal and financial service and the construction of new agricultural management system are not coordinated on the basis of measuring synergy degree. Finally, the paper puts forward some suggestions about synergy effects of fiscal and financial service supporting the construction of new agricultural management system to achieve agricultural transformation and upgrading. According to the study, we find that existing fiscal and financial aid-agriculture service is built on rural household management.In the process of transforming traditional agriculture management to modern agriculture, constructing new agricultural management system will bring huge investment risk and uncertainty which will make the existing fiscal and financial services and the construction of new agricultural management system inconsistent.so it is necessary to promote fiscal and financial services innovation in order to ensure the synergy between fiscal and financial service and the construction of new agricultural management system. In fact, the synergy is a new equilibrium relationship between supply and demand of fiscal and financial services.