A comprehensive and accurate thermodynamic database for Al 6xxx series alloy encompassing Al-Mg-Si-Cu-Fe-Mn-Cr has been developed based on the critical evaluation and optimization of all available literature data and new phase diagram experiment. Based on this database, the thermodynamic calculations are performed to understand the phase evolution during casting, homogenization and final tempering process. In particular, the equilibrium phase fraction diagrams of all the possible precipitate phases are mapped in the composition range of 0-1.1 wt.% Mg and 0-0.7 wt.% Si at various processing temperatures. The influence of the variation of minor alloying/impurity elements such as Cu, Fe, Mn, and Cr to the amount of each type of precipitates is also taken into account. Considering conventional Al processing technologies from casting, homogenization, extrusion, and final age-hardening stages, the calculation results will be interpreted for logical Al alloy design.