Selecting appropriate mid-model is critical for high efficiency of model transition and data migration between relational databases and NoSQL databases. We explore the problem of uniform mid-model design used for model transition and data migration between relational databases and NoSQL databases. Our suggested approach proposes a complete process. We use data features and query features to generate a mid-model. And through predefined strategy, we transfer mid-model to physical model of destination database. After establishing this mapping, we can migrate data from source databases to destination databases.