Abstract: The Martian atmosphere consists of up to 95% carbon dioxide（CO₂）. Developing technologies that enable efficient decomposition of CO₂ into oxygen（O₂）and carbon monoxide（CO）via redox reactions can substantially reduce the need for transporting life-support consumables such as oxygen from Earth, thereby significantly lowering the cost of future crewed missions. Conventional approaches to CO₂ conversion predominantly rely on high-temperature（electro）chemical processes. Thermal decomposition of CO₂, however, requires extreme operating conditions, leading to low energy utilization efficiency and further complications caused by gas-phase separation effects under microgravity. Moreover, the composition of reaction products is strongly influenced by electrode materials, structures, and operating parameters, which collectively result in relatively low overall CO₂ conversion efficiency. To address the major limitations of current in-situ CO₂ utilization technologies—including bulky system volume and mass, high energy consumption, low energy-to-matter conversion efficiency, and insufficient O₂ recovery—we propose an advanced electron cyclotron resonance（ECR）low-temperature plasma catalytic method for CO₂ reduction. By overcoming the inherent cutoff-size effect in microwave transmission, we designed a compact resonant cavity chamber with a reaction scale of approximately 49 mm. This configuration achieves high-efficiency conversion of microwave energy and, under ultralow power conditions, surpasses the electrochemical oxygen production conversion limit of 50%. The successful development of this system provides a fundamental technological basis for the design of next-generation, high-efficiency, and stable prototypes for oxygen generation from Martian atmospheric CO₂. Such advancement constitutes a critical step toward establishing a sustainable human presence on Mars. Beyond planetary applications, this technology also holds potential for long-duration oxygen production in closed-loop environments, such as orbital space stations and underwater submarines, where life-support resources must be continuously recycled.