Abstract: From the perspective of heterogeneous beliefs, this paper constructs an asset pricing model that includes three types of agents: fundamental traders, technical traders, and stabilizers. By integrating data from the CSI 300 Index with multi-scenario numerical simulations, it examines the mechanisms through which government intervention and market sentiment influence the stability of the A-share market. The findings are as follows: First, government intervention can effectively guide prices back to their fundamental values, thereby avoiding excessive price distortions. Second, sentiment exerts a unique "restraining effect," which facilitates adjustments in investor structure and helps stabilize fluctuations. Third, the interaction between sentiment and government intervention leads to prolonged fluctuations in the proportion of heterogeneous agents, significantly slowing the rate of convergence. This deeply reflects the multi-party game inherent in market rescue operations. Based on these findings, this paper proposes corresponding policy recommendations to enhance market stability and mitigate systemic financial risks.

Key words: Government Intervention, Sentiment, Heterogeneous Beliefs, Market Stability, Asset Pricing