Abstract: African resource-rich countries have intensively introduced “local beneficiation” policies centered on export restrictions as the primary tool and driven by the fundamental objective of upgrading local value chains, posing systemic challenges to China’s supply security of critical minerals. To systematically assess the degree of policy impact and risk differentiation, this study reviews the evolution of “local beneficiation” policies in ten African countries and the African Union from 2020 to 2026. Employing quantitative methods including the Policy Intensity Index（PII）, Herfindahl-Hirschman Index（HHI）, and Supply Risk Index（SRI）, combined with typical case tracking, it constructs an analytical framework of “policy shock-vulnerability identification-impact analysis-risk assessment”. The findings reveal the following: ①Africa’s local beneficiation policies have progressively escalated between 2020 and 2026, expanding from single-mineral raw ore export bans to comprehensive bans on concentrates across multiple minerals, while policy instruments have evolved from blanket prohibitions to combined control measures such as quotas and tariffs. ②The HHI values for China’s import sources of six critical minerals all exceed 2 500, indicating a systemic risk of supply concentration. ③Export restrictions will impact China’s critical mineral supply security through three dimensions—contraction of raw material supply, transformation of investment models, and the superposition of great-power competition—with the Supply Risk Index（SRI） for cobalt reaching 0.98, placing it in the extremely high-risk category, and the policy-incremental risk（ΔSRI） amounting to 0.30. ④Chinese mining enterprises are transitioning from a “mining-shipping back” model to a “mining-local processing-product export” model, reflecting a profound transformation in the underlying logic of China-Africa mining cooperation. Based on the above findings, this study proposes targeted policy recommendations, including actively integrating into Africa’s “local beneficiation” strategic framework, building a diversified supply security system, improving the risk early-warning mechanism for critical mineral supply chains, and deepening the mining cooperation mechanism under the Forum on China-Africa Cooperation, aiming to enhance the resilience of China’s critical mineral supply chain, safeguard mineral resource security, and promote high-quality development of China-Africa mining cooperation.