To ensure the long-term security and reliability of the power system, the design of a capacity adequacy mechanism has become a critical component in electricity market development. This paper systematically reviews mainstream international capacity adequacy mechanisms, and proposes a combined capacity mechanism framework alongside its core mechanism—the revenue-based reliability option，which is the revenue-option based combined capacity mechanism. The combined capacity mechanism adopts a dual-layer structure integrating centralized and decentralized approaches. The centralized segment provides stable revenue guarantees for new generation units through long-term revenue-based reliability option auctions, while the decentralized segment ensures short-term resource allocation efficiency via capacity obligations and certificate trading. In view of the immaturity of China electricity market, this paper further proposes a four-stage revenue-option based combined capacity mechanism development path, and designs in detail the revenue-based long-term contract spanning the first three stages, laying the foundation for the future transition to the fourth stage of the mature revenue-option based combined capacity mechanism.