The invention discloses an HBase-based heterogeneous database online exchange and sharing system in a big data environment. The system comprises a heterogeneous database unified access component, a data collection module, a data mapping module, a data conversion module, a data fusion module, a data distribution module and a data delivery module. The heterogeneous database unified access component provides a unified database access interface; the data collection module collects data in a source database; the data mapping module establishes a mapping relation between all heterogeneous databases and a unified semantic sharing model; the data conversion module realizes data conversion; the data fusion module fuses the unified semantic sharing model with a unified semantic sharing model of historical data and stores a fused model into an HBase intermediate database; the data distribution module sends to-be-exchanged field data to the data conversion module according to a timestamp; the data delivery module pushes the data to a corresponding target database. Through the system, automatic online exchange and sharing of mass data between the heterogeneous databases are realized, and exchange and sharing efficiency is high.