The finance and tax authorities have issued a series of preferential support policies aimed at encouraging financial institutions to increase the credit supply of small and micro businesses. This paper takes 84 banking institutions in Heilongjiang province as samples to evaluate the effect of fiscal and tax support policies for small and micro credit qualitatively and quantitatively. The results show that the fiscal and tax support policies of small and micro credit have defects in top-level design and specific preferential standards, resulting in limited incentive effect on banking institutions and low influence weight on the decision-making of banking institutions. Therefore, it is necessary to further clarify the support focus and direction of fiscal and tax policies for small and micro credit and adjust the support methods, so as to enhance the systematization, simplicity and convenience of the policies. At the same time, it is necessary to perfect and adjust the specific standards of fiscal and tax support policies for small and micro credit from three perspectives of small and micro credit.