Abstract: The special color coating on steel sheets or members could be obtained in hot galvanization processing while the bath contains some transitional elements together with the cooling control. Understanding its coloration mechanism from a thermodynamic point of view is helpful for further bath composition optimization due to its potential industrial application. The effects of the main solute elements and impurities in the zinc bath on its excess thermodynamic properties were investigated through the Miedema model and Tanaka relationship together with some basic thermodynamic equations. The results indicated that the activities of solute elements in the bath are closely related to its color generation feature. The effects of solute concentration and hot dip temperature on the bath coloration ability should owe to their effects on the solute activities in zinc bath. The effects of impurities such as Al and Mg and color generation solute Ti are related with their effects on the solvent activity.