Electric power is vital for the national security, economy, and people's livelihood of a country. Ensuring the stable and secure supply of electric power is crucial for achieving carbon peaking and carbon neutrality. Therefore, it is imperative to analyze the weaknesses and challenges of power supply security in China and construct a power supply guarantee system that adapts to the new era and facilitate high-quality economic development. Herein, the research progress of power security supply is reviewed, the current status of power supply in China is summarized, and the trend in power security supply in China during the 14th Five-Year period and for the medium and long terms is analyzed. Moreover, considering the recent power rationing incidents, the problems and challenges for power supply in China are summarized and analyzed. On this basis, the basic principles of adhering to security first, a low-carbon path, market-oriented reforms, and technological innovations are proposed, and a three-step roadmap for constructing a new power supply guarantee system is investigated. Furthermore, we propose the following suggestions: (1) enhancing China's power supply guarantee capabilities to solidify its foundation for power supply security; (2) improving the intrinsic security of power supply by focusing on the demand side; (3) establishing a new-generation technical system for guaranteeing power supply security; and (4) optimizing the market system to construct a power security ecology participated by all.