Abstract: In the context of emergencies, finance is the ultimate guarantee for all government actions, and the legalization of emergency fiscal expenditures is the institutional basis for demarcating the main responsibilities and alleviating social risks. Focusing on China’s existing emergency fiscal regulation system, the legalization of emergency fiscal expenditures in the post-epidemic period is confronted with four major obstacles: two-way misplacement of the regulatory system, excessive subsidence of expenditure responsibilities, detailed imbalance of emergency fiscal power and authority power, and expenditure under the statutory budget form rigidity. Straightening out the supporting relationship among “rules-funds-theories”, the three are linked to guide the legalization of emergency fiscal expenditures. In order to solve the above problems, it is necessary to base on the perspective of inter-law integration, combine the theoretical basis of the legalization of emergency fiscal expenditures, depend on the principle of system distribution, and divide the central and local emergency fiscal expenditure responsibilities together with the comprehensive administrative level and the incident hazard level; to integrate and coordinate emergency management norms and fiscal expenditure systems along the five stages of “prevention-mitigation-rescue-rehabilitation-evaluation”; to realize the formal and substantive setting of authority power and financial power based on the principle of publicity; to use anti-intellectual thinking to guide the reservation of budget flexibility. With a view to solving the above-mentioned problems one by one, sufficient reserves of legal system is needed to deal with social risks.