Thermodynamic databases are indispensable in providing phase equilibria and phase transformation for new alloys design and process optimization. The quality of calculated results is strongly dependent on the accuracy of the thermodynamic database. A thermodynamic database for multicomponent copper alloys has been developed, which contains 30 elements covering the major and minor alloying elements of most commercial copper alloys. About 330 binary and 60 ternary systems have been assessed over the entire composition range. Examples of assessments and calculations for typical binary and ternary systems were presented. A wide range of compositions from pure copper to complex commercial copper alloys can be calculated. Scheil solidification simulations were carried out using the thermodynamic database for predicting the phase formation sequence during solidification, as well as phase compositions and phase fractions. In conjunction with a compatible kinetic database, the present established thermodynamic database was used to simulate the microstructure evolution of copper alloys during the ageing process. The simulated results were verified by key experiments, which proves the accuracy of the thermodynamic database established by us.