Financial security is the foundation and guarantee of economic security. The reform of the county under the direct management of the Ministry of Finance is an important barrier to construct county-level fiscal security defenses and an important way to explain the financial security of local governments in China. This paper selects Shanxi Province as a typical case, and takes the direct management of the Ministry of Finance as a quasi-natural experiment to examine the policy effect of fiscal decentralization reform on the balance of fiscal revenue and expenditure at the county level. Adopting a combination of propensity score matching and double difference method (PSM+DID) to identify the causal effect of reforms on county-level fiscal revenue and expenditure ratios, and from three perspectives: social resource integration capability mechanism, internal motivation mechanism and external pressure mechanism The internal mechanism of the causal disposition effect is verified. Research has shown that the reform of the counties directly under the direct management of the Ministry of Finance has significantly increased the fiscal revenue and expenditure ratio of the pilot counties by 6 percent, and the policy effects are lagging and sustainable. This conclusion is still valid after changing the measurement method, replacing the sample, and testing the placebo. This article provides an explanation path for understanding local fiscal security from the perspective of fiscal system reform, and provides a theoretical basis for continuing to advance and deepen the reform of counties under the direct management of the fiscal province.

财政安全是经济安全的基础和保障。财政省直管县改革是构筑县级财政安全防线的重要屏障,是解释中国地方政府财政安全的重要途径。本文选取山西省作为典型案例,以财政省直管县为准自然实验,考察了财政分权改革对县级财政收支平衡度的政策效应。采取倾向得分匹配与双重差分法相结合 (PSM+DID)的方式,识别出改革对县级财政收支比的因果处置效应,并从社会资源整合能力机制、内部动力机制和外部压力机制三个角度验证了因果处置效应的内在机理。研究表明,财政省直管县改革显著提升试点县6个百分比的财政收支比,且政策效应具有滞后性和持续性。这一结论在通过改变计量方法、更换样本以及安慰剂检验后依然成立。本文从财政体制改革角度为认识地方财政安全提供了解释路径,为持续推进和深化财政省直管县改革提供了学理依据。