Abstract: In the digital era, data, as a critical factor of production, is essential for economic growth, technological innovation, and enhancing corporate competitiveness. Traditional centralized data trading systems pose a series of data and transaction security risks. Although decentralized data trading systems based on blockchain technology have emerged, which can guarantee security for data transactions through blockchain and smart contracts, systems based on blockchain still struggle with cross-regional, cross-domain, and international data transactions. They primarily face the following three challenges: 1) Consistency of cross-domain identity resolution results. 2) Availability of cross-domain identity resolution services. 3) Security and compliance issues for cross-domain data trading systems. To address these issues, we design a secure and efficient cross-domain identity resolution mechanism based on decentralized identity technology and construct a secure, regulated decentralized data trading system based on this mechanism. The identity resolution mechanism includes a set of cross-domain protocols that ensure the consistency of resolution results and an incentive mechanism that ensures the availability of services executing these protocols. The decentralized data trading system supports granular regulation based on identity attributes and ensures the atomicity of cross-domain data transactions. Experimental verification shows that this system meets the design targets. By batch constructing cross-domain resolution requests, the identity cross-domain resolution protocol and caching mechanism can ensure the correctness of the resolution results, with the resolution latency being only 45% of the cross-domain resolution latency. Additionally, the cache can increase the hit rate by 72% through active and passive update mechanisms. The system is also compatible with multiple blockchain systems, and cross-domain data transactions can be completed within an average of 2.3 blocks, making the system efficiency within an acceptable range.