Global warming has intensified the frequency of heatwave events (HWE), posing significant challenges to public health systems. This study evaluates the impact of HWE on public health expenditures (PHE) in China and explores mitigation mechanisms to inform climate-resilient policies. Utilizing panel data of 238 cities from 2011 to 2020, this paper employs a two-way fixed effects model and a moderating effects model, complemented by robustness checks and heterogeneity analysis. Results reveal that HWE significantly increase PHE. Heterogeneity analysis highlights that large cities are confronted with heightened vulnerability, while cities with a high proportion of outdoor workers also face more health risks. Moderating effect tests demonstrate that green technological innovation and park green spaces effectively mitigate HWE-driven PHE growth. The study recommends integrating climate risks into public health budgeting, prioritizing green technology adoption, and advancing ecological urban planning to enhance urban resilience and reduce health inequities. These findings offer empirical support and policy insights for developing countries addressing climate-induced health-economic burdens.