Deepening supply-side reform is of great significance to promoting high-quality development on the supply side. Taking a-share listed companies from 2007 to 2019 as the research object, this paper explores the influence of heterogeneous institutional investors on commercial credit financing. The results of this study show that the scale of commercial credit of enterprises held by institutional investors can be improved by improving the quality of information disclosure. The shareholding of focused institutional investors plays a more significant role in promoting commercial credit financing. The results remained robust after using substitution variables, propensity score matching method, substitution variable measurement method, one-stage lag and instrumental variable method. Further analysis shows that focused institutional investors can only promote the commercial credit financing of enterprises with strong R&D intensity. Institutional investors play a better governance role in enterprises with weak marketization process and high financing constraints. This paper reveals the black box of institutional investors'' influence on corporate commercial credit financing, and suggests that the capital market develop focused institutional investors with stable shareholding and high shareholding ratio, improve the scale of commercial credit financing, and promote high-quality development of the supply side.