To deal with information incompleteness or error and supervising difficulties caused by hardships in information synergy and sharing among current medical institutions, this article proposes a solution to construct a city's smart-heathcare data system. Through the design of synchronizing each medical institution's heterogeneous database to data center, the aforementioned problems are solved. By analyzing the needs of city's medical data center, this article takes NoSQL database and hadoop as the basis of system construction. Meanwhile, through comparative analysis of several existing NoSQL databases, Habase is found suitable for storing and processing massive data. This article proposes a new database modeling thought, O-R (Object Relationship) modeling, by reference to E-R relational database modeling. This O-R modeling thought compensates for non-relational databases' deficiencies in front of relational databases. Utilizing this new modeling thought and the solution to synchronize heterogeneous databases identically to data center, the article completes the construction of the city's smart-heathcare data system.