Since the initiation of the registrationbased IPO reform pilot, prospectuses of IPO applicants have been criticized for low readability and insufficient relevance to investors decisionmaking. In response to these concerns, the China Securities Regulatory Commission (CSRC) issued a dedicated policy guidance document in early 2022. While the guidance aims to enhance prospectus disclosure quality by strengthening the supervisory framework for information disclosure, its character as an “interpretation of regulatory philosophy”, without direct legal enforceability over market participants. Consequently, its implementation faces numerous practical challenges, and evidence on its actual effectiveness remains scarce. Leveraging the temporal gap between the submission of preliminary prospectus drafts and the subsequent hearing versions, this study constructs a quasinatural experiment to evaluate the impact of the guidance. The empirical results reveal that, relative to IPO applicants who had submitted their hearing drafts prior to the guidance, those submitting afterward exhibited significantly improved disclosure quality, as reflected in both readability metrics and indicators of relevance to investment decisions. The effect is particularly salient among applicants whose hearing drafts submitted after the guidance were still subject to exchange comment letters, highlighting the critical role of interim supervisory interventions as an enforcement mechanism. Moreover, we document that IPO applicants submitting their final prospectuses subsequent to the issuance of the guidance experienced lower underpricing rates and turnover rates. This evidence suggests that the interpretation of regulatory philosophy regarding IPO information disclosure quality mitigates information asymmetry and divergence of opinions among investors regarding IPO applicants, thereby contributing to the efficiency of resources allocation in the capital markets.