Compared with the mature capital markets of foreign developed economies, the development of China’s capital market is relatively backward, the construction of various systems is not very perfect, and asset mispricing due to information asymmetry and other reasons is a common phenomenon in the securities market. How to alleviate the phenomenon of asset mispricing and ensure the full play of the optimal allocation of capital in the stock market is an important issue worth exploring and researching. Based on behavioral finance theory and information asymmetry theory, existing studies have analyzed the influence factors of asset mispricing from the perspective of corporate internal and external governance, but there is little literature on the impact of corporate diversification on asset mispricing from the perspective of corporate strategic behavioral decision-making based on the information perspective. This paper selects A-share listed companies in Shanghai and Shenzhen from 2011 to 2022 as the research object, adopts relevant data from CSMAR and Wind database, and draws on the calculation method of asset mispricing by Xu Longbing and Xu Shoufu (2015) and the calculation method of diversification by Yang Xingquan et al. (2020) to get the key research variables in this paper, and explores whether and how the diversification strategy of enterprises affects asset mispricing. The study finds that diversification mitigates the degree of asset mispricing, and the impact of unrelated diversification on asset mispricing is more significant than that of related diversification; the analysis of the mechanism of action from the perspective of information transfer shows that the surplus management behavior of enterprises and the accuracy of analysts’ surplus forecasts play a mediating role in the effect of diversification on asset mispricing; and the final analysis of heterogeneity finds that the mitigating effect is more significant in SOEs and less market-oriented regions and management power and institutional investor shareholding also strengthen the effect of diversification on asset mispricing. Compared with existing studies, the contribution of this paper is mainly reflected in: (1) From the perspective of stock pricing, it provides new evidence for the economic consequences of diversification of listed companies in China, and tries to explore the role of diversification in influencing the pricing efficiency of the capital market, which not only provides more rigorous evidence of the relationship between diversification and asset mispricing, but also expands the related research on the economic consequences of diversification. (2) This paper provides an in-depth and comprehensive examination of the impact of diversification on the pricing efficiency of China’s capital market by exploring whether different types of diversification play different roles in the pricing efficiency of the capital market. (3) By exploring the influencing factors of asset mispricing from a new perspective, breaking the limitations of existing studies focusing only on investor characteristics, internal and external regulatory mechanisms of firms, and examining how diversification acts on asset mispricing from the perspective of firms’ strategic behaviors through the information diversification hypothesis and the information transparency hypothesis under the information perspective, this paper provides new evidence of the impact of corporate strategies on asset pricing under in the Chinese scenario. The findings of this paper reveal the impact of diversification on the capital market of listed companies in China, affirm the advantages of diversification in improving pricing efficiency, and have certain reference values in theory and reality.