The regional medical information sharing system is a very important way to promote the medical and health reform and the higher level of medical and health service. In order to solve the issue of sharing the information with each other medical institution, this article integrated the domain-engineering idea into the building of regional medical sharing information system. According to the basic requirement of SOA (Service Oriented Architecture), this article analyses the fundamental structure of regional medial sharing information system based on SOA, and then researches the software architecture of regional medical sharing information system on the basis of domain engineering.