金融支持小微企业健康发展是打通流通堵点，加快“双循环”新发展格局形成的重要基础。已有研究表明定向降准政策能从整体上支持小微企业融资，但由于信贷周期存在结构效应，定向降准政策能否有效支持县域小微企业仍需探讨。运用信用创造理论、贷款定价比较优势原理和马克思的流通经济论，先剖析定向降准政策影响县域小微企业贷款量、贷款成本及企业与供应链的紧密程度影响政策效果的理论机理。在此基础上，运用2011-2019年新三板小微企业数据，在倾向得分匹配的基础上采用双重差分方法进行实证分析。结果表明，定向降准政策的实施能够促进县域小微企业提升贷款量并降低其贷款成本。定向降准政策的增量和降价效果存在区域和行业异质性，三农部门中的小微企业受到的政策支持不多。相较于供应商，县域小微企业与客户关系越紧密，其受到贷款量提升作用更强。

Supporting small and micro enterprises’ smooth operation with financial tools is an important basis for removing circulation blockage and promoting the formation of a new development pattern of "double circulation". Existing studies have shown that the targeted RRR reduction policy can support the financing of small and micro enterprises wholly, whereas the structural effect of credit funds and the weak sustainability of policies remain to be discussed. Applying the credit creation theory, the principle of comparative advantage of loan pricing and Marx's theory of circulation economy, the theoretical mechanism that the targeted RRR policy affects the loan volume, loan cost of small and micro enterprises in counties and how closeness between enterprises and supply chain work in the policy implementation are analyzed. Employing the data of small and micro enterprises on the National Equities Exchange and Quotations from 2011 to 2019, the empirical analysis is carried out with the difference-in-difference method on the basis of propensity score matching. The empirical results show that the implementation of the targeted RRR reduction policy can promote the county small and micro enterprises’ credit volume increase and loan cost reduce. There are regional and industrial heterogeneity in the effect of the targeted RRR reduction policy, and small and micro enterprises in the agricultural and rural sectors receive little policy support. Compared with supplier relationship, the closer the relationship between small and micro county enterprises and customers, the stronger the improving effect in credit volume.