By referencing the subject data storage idea in the areas of data warehouse and service-oriented analysis method, we proposed a two-stage method to create SOA-based data model including: (i) building a subject domain E-R data entities model, and (ii) building service data model. We described the data model from the layered point of view, where three layers are physical data layer, data aggregation layer and cross-organization services aggregation layer. In the development of the Distance Open Education Information System, we used this method to analyze and establish the system data model.