In policy communication practice, exploring the impact of ambiguous policy communication on investor expectations and market stability is with significant theoretical and practical relevance. Using a learning-to-forecast experiments, this paper distinguishes between two dimensions of policy communication information: the policy trigger dimension and the adjustment scale dimension and examines the impacts of ambiguous communication from either dimension. The experimental findings reveal that reducing ambiguity in the policy trigger dimension significantly enhances asset price stability, while reducing ambiguity in the adjustment magnitude dimension either fails to enhance or may even destabilize asset prices. This counterintuitive result suggests that the effects of ambiguous communication are dimension-specific; Thus, minimizing ambiguity in the policy trigger dimension while maintaining it in the adjustment magnitude dimension can effectively bolster the stabilizing impact of policy communication. Furthermore, we examine the mechanisms underlying these dynamics by analyzing market participants’expectation formation strategies. Results indicate that when ambiguity arises from the adjustment magnitude dimension, participants are more inclined to adopt adaptive expectation strategies—leading to greater price stability—while being less likely to employ trend-following strategy or learning, anchoring and adjusting strategy, which are associated with greater price instability. Our analysis contributes to the understanding of heterogeneous market responses to varying dimensions of policy communication ambiguity.