The improvement of enterprises' long-term value helps increase investor returns, promote the coordination of investment and financing, and strengthen financial support for the development of the real economy. Against the background of digital transformation, the exploration of the relationship between enterprises' strategic disclosure and their long-term value is of great practical significance. Sampleing from Chinese A-share listed companies in Shanghai and Shenzhen between 2015 and 2023 were utilized. The findings are as follows. Firstly, strategic disclosure has a significant negative impact on enterprises' long-term value. This result remains valid after multiple endogeneity and robustness tests, such as the instrumental variable method, PSM, and variable replacement. Secondly, mechanism analysis shows that strategic disclosure related to digital transformation significantly reduces investor sentiment, the quality of analysts' earnings forecasts, and the competitive advantage in the product market, thereby reducing enterprises' long-term value in multiple aspects. In addition, heterogeneous characteristics reveals that the negative impact of strategic disclosure on enterprises' long-term value is more significant when enterprises face higher external environmental uncertainty and are in the growth or mature stage. Further analysis indicates that strategic disclosure also exerts a significant negative effect on enterprises' investment efficiency. Among the two dimensions of "more words" and "fewer actions", "more words" has a greater negative impact on long-term value. The conclusions provide enlightenment for improving corporate efficiency, optimizing corporate governance, and promoting high-quality development.