Under the registration system, inquiring from institutional investors is a key step in the IPO process on STAR Board. Using the sample of IPOs on the STAR Board from 2019 to 2023, the paper empirically examines the impact of Key Audit Matters(KAM) disclosure on the divergence of institutional investors. The research finds that the more KAM are disclosed, the greater the divergence of institutional investors’ opinion, and the new rules for inquiry reinforce the positive correlation. Further analysis reveals that more detailed or more precise KAM disclosed lead to greater investor divergence, while negative tones reduce divergence. The enhancing effect of KAM on the divergence of institutional investors’ opinions is primarily observed in IPOs audited by the “Big Ten” audit firms, with domestic institutional investors exhibiting greater divergence in opinions.Therefore, regulatory authorities should urge accounting firms to enhance the disclosure of KAM and encourage institutional investors to actively participate in inquiring to improve the pricing efficiency of IPOs under the registration system.