Hospital Information System (HIS) is flourishing vigorously in China, but the hospital information isolated islands, steered by software producers and operated independently in each hospital, have seriously restricted wide popularization and profound reformation of HIS. Nowadays, the integration and interconnection of HISs has become a critical problem we have to face in the digital hospital construction. Based on the software architecture theories and practices, this paper proposes a regional HIS interconnection runtime architecture which is based on Electronic Medical Record (EMR), discusses a EMR conceptual architecture to guide EMR system research and development, and presents a technical architecture to implement open HIS interconnection in a region. The three architectures together provide a comprehensive technology-enriched reference architecture for the new generation of HIS research and development which is loosely coupled, patient-centered and region-oriented.