本文以2009-2012年间沪深两市A股上市公司数据为样本，使用层次回归模型，研究了企业所得税与研发支出的关系，考察了资本结构对二者关系的调节效应，并进一步检验了产权性质的影响。研究结果表明，企业所得税对研发支出具有显著负向影响；由于债务税盾的存在，资本结构能够缓解企业税负对研发支出的约束；而且，资本结构对所得税与研发支出之间关系的调节效应在非国有企业中更为显著。这些结论突破了以往单独研究所得税或资本结构对研发支出影响的局限性，为企业研发投资决策和资本结构选择提供了新的理论证据。

Based on the sample of Chinese public listed companies from 2009 to 2012, using the hierarchical regression model, this study examines the relationship between the corporate income tax and its R&D expenditure, analyzes the moderating role of capital structure on the relationship of them, and further examines the influence of different property rights. The results show that there is a negative relationship between the income tax and the R&D expenditure, and because of the impact of debt tax shield, the capital structure could relieve the constraints of tax burden on R&D expenditure. And the moderating effect of capital structure is more significant on non-state-owned corporations. This study makes a breakthrough of separately analyzing the relationship between R&D expenditure and income tax or capital structure, which may provide new evidence for the decisions of R&D investment and the choice of capital structure.