Abstract: In response to the escalating challenges posed by anthropogenic climate change to ecosystems, policy environmental impact assessment (EIA) has emerged as a crucial instrument for achieving climate objectives and strengthening policy resilience, owing to its cross-sectoral and trans-regional macro-perspective coupled with unique advantages in cumulative impact evaluation. This study systematically employs literature review and case analysis to evaluate the rationale for synergistically integrating both climate change mitigation and adaptation into policy EIA frameworks. Based on the empirical analysis of 17 pilot policy EIA cases in China, the research uncovers multiple institutional deficiencies and barriers in the implementation process of climate change assessment, including a pronounced mitigation-over-adaptation bias, a lack of adaptation assessment methodologies, inadequate data infrastructure, and disproportionate attention across different policy levels and categories. In light of these limitations inherent to this initial exploratory phase, the study proposes concrete policy recommendations and technical pathways to improve China's policy EIA and climate change integration mechanism. These include strengthening the legal-regulatory framework, building a climate change assessment technology system, and optimizing climate change models and data transparency. This will facilitate China's strategic transition from an active participant to a global leader in climate governance.