ABSTRACT Based on the sample of listed companies in China, this paper discusses the impact of the annual report inquiry letter sent by stock exchanges on stock price informativeness. Research results show that the inquiry letter increases the stock price non-synchronicity, indicating a positive impact of the inquiry letter on stock price informativeness. This effect is more pronounced for companies with low information transparency and poor corporate governance, suggesting that inquiry letter increases stock price informativeness through the information channel and governance channel. The positive impact of inquiry letter on stock price informativeness is affected by the frequency of receiving inquires, whether accounting firms are required to express verification opinions and the number of questions in the inquiry. Results of this paper support the positive role of inquiry letter in improving market information efficiency.