Information disclosure is the core of the registration-based IPO reform. Using the pilot implementation of the registration-based IPO reform on China’s Growth Enterprise Market (GEM) as the research setting, we construct a multi-dimensional measure of information disclosure quality based on accuracy, readability, and completeness. and employ a difference-in-differences (DID) approach to examine the impact of the registration-based system on the quality of information disclosure among IPO firms. The results show that, overall, the registration-based IPO reform improves the quality of IPO firms’ information disclosure. A more detailed analysis reveals that the reform enhances the readability and the completeness but has no significant effect on the accuracy of information disclosure. The positive impact of the reform on readability and completeness is more pronounced when underwriters have higher reputations and executives receive stronger incentives. Mechanism tests indicate that the reform influences information disclosure quality by strengthening regulatory constraints and enhancing pricing incentives. Further analysis demonstrates that, by improving information disclosure quality, the reform effectively enhances market pricing efficiency and increases IPO firms’ long-term returns after listing. Our research contributes to the literatures on the policy effects of the registration-based system implementation and provides empirical evidence and policy insights for further optimizing the reform.