Abstract: Mergers and acquisitions (Hereinafter referred to as M&A) behavior as a major production and operation decision of the enterprise, the role of heterogeneous institutional investors needs to be further inspected. This paper selects a sample of state-owned enterprises（Hereinafter referred to as SOEs）′ M&A to examine the impact of heterogeneous institutional investor shareholders on the high-leverage SOEs′ M&A behavior. The results show that institutional investors can significantly inhibit the possibility of high-leverage M&A, but stable institutional investors cann′t significantly inhibit the possibility of high-leverage M&A; institutional investors can significantly inhibit the size of M&A by high-leverage enterprises, and the shareholding level of large shareholders and the correlation of M&A can reduce the above-mentioned inhibition, while the impact of stable institutional investors on the size of M&A of high-leverage enterprises shows better stability. Therefore, stable institutional investors can influence the scale of M&A more effectively through enterprises internal decisions than all institutional investors.

Key words: institutional investors, SOEs′ M&A, leverage level