Based on the data of China Micro and Small Enterprise Survey,the motivations of small and micro enterprises" financial leasing transactions were explored from the perspective of tax and financing constraint. The empirical results show that both the classic foreign “tax rate difference theory” and tax-saving incentives cannot effectively explain the financial leasing transactions of Chinese small and micro enterprises. The aim of small and micro enterprises" financial leasing transactions is to ease their financing constraints. Further research finds that the influence of financing constraints on small and micro enterprises" financial leasing transactions depends on the development stage of the enterprise and the condition of the legal environment in the region. This paper provides empirical evidence of the motivation of small and micro enterprises" financial leasing transactions, and proposes insights for easing small and micro enterprises" financing constraints from the perspective of enriching financial products and tools.