2015年我国正式开启了国地税合并改革。文章以2015年为断点，采用模糊断点回归方法，以会计年度与2015年的距离度量改革的渐进过程，研究国地税合并后税收竞争对我国民营企业投资效率的影响。研究发现，国地税合并提高了税收征管水平，抑制了地方政府间的恶性税收竞争，优化了民营企业营商环境，提高了民营企业投资效率。今后，中央政府在制定规则时应更加注重社会公共利益的实现，而地方政府间的税收竞争也应把握好“度”的问题。此外，还应综合评估国际形势及影响，从国际经济关系与经济全球化视角审视税收竞争的经济效应，并根据公共服务均等化和区域协调发展目标合理选择税收工具。

In 2015, China started the process of the merger of national and local tax authorities. This paper uses private listed companies from 2002 to 2019 as the research sample, and uses the fuzzy regression discontinuity to study the effect and mechanism of tax competition on the investment efficiency of Chinese private enterprises after the merger of national and local tax authorities. The study shows that the merger of national and local tax authorities has improved the level of tax collection and management, thereby inhibiting malicious tax competition among local governments, optimizing the business environment, and improving the investment efficiency of private enterprises. In the future, the Central Government of China should pay more attention to the realization of social public interests when making rules, and the tax competition among local governments should also properly manage the issue of "degree". In addition, it is necessary to comprehensively assess the international situation and impact, examine the economic effects of tax competition from the perspective of international economic relations and economic globalization, and rationally choose tax tools according to the goals of equalization of public services and coordinated regional development.