Abstract: Credit rating is often considered a vital early warning indicator for corporate bond default risks, and the accuracy and forward-looking nature of credit ratings are crucial to promote the healthy development of the bond market. This study examines the effectiveness of corporate credit ratings as an early warning signal for bond defaults by analyzing bond default data from non-financial listed enterprises in China. Additionally, the study delves into the problem of inflated and distorted credit ratings. The findings reveal that the early warning effect of corporate credit ratings on bond defaults is not significant. Moreover, when credit ratings change from high to low, the early warning effect becomes weaker. A higher credit rating in the low credit rating range significantly increases the probability of default. Further analysis indicates that credit ratings cannot accurately reflect fundamental and macroeconomic information of enterprises, leading to distorted rating information.