Based on the special stock exchange comment letter system in China, this paper explores the relationship between the exchange tax-related comment letters and corporate tax avoidance behavior from the standpoint of securities regulation. We document that firms that engage in more aggressive tax avoidance are more likely to receive a tax-related exchange comment letter. Also, relative to firms receiving a non-tax-related comment letter, firms receiving a tax-related comment letter reduce their tax avoidance behaviors in subsequent years. Further study shows that the more the number of questions and the greater the level of detail in the comment letter, the stronger the effect of tax-related comment letters on corporate tax avoidance. After examining the sample with different degrees of political connection, we find that tax-related comment letters inhibit tax avoidance among state-owned enterprises and private enterprises with close political connections. Finally, the monitoring effect of comment letters on corporate tax avoidance is more pronounced in regions where tax administration is weak, suggesting that the comment letter system can be used as a complementary mechanism for tax administration.