Purpose /Significance To systematically analyze the connotation and boundary of the“data domain”，and to provide theoretical support for the policy practice of the“data remains within its domain” . Method /Process Through policy document analysis，conceptual definition，and empirical research，the connotation and extension of the“data domain”are clarified. By unifying the data governance logic and security responsibility boundaries，the Shenzhen medical artificial intelligence innovation platform and the regional health information platform are incorporated into the same logical domain，and privacy computing technologies are employed to reconstruct the security system. Result /Conclusion Under unified management entities and security responsibility boundaries，the trusted data space can balance the requirements of“data remains within its domain”and the release of data value，providing an application paradigm for the circulation of medical data elements.