It has great significance to investigate the degradation of aromatic contaminants as they are highly carcinogenic and nondegradable pollutants in drinking water. In this paper, the mineralization orders of the representative nitro/chloro/methyl/amino-aromatic contaminants with oxidants (OH, H2O2, O-, O2,O3) in advanced oxidation processes (AOPs) are investigated based on the calculated standard molar Gibbs free energy changes of reaction (ΔrGm0) and the results are consistent with those from previous experimental results, electrophilic substitution orientation rules of the Hammett equation, and predicted results with a quantitative structure-activity relationship (QSAR). In addition, the quantitative function relationship between the degradation rate (r) of the aromatic contaminants and the thermodynamic driving force (ΔrGm0) is analyzed in order to investigate the degradation kinetics more rigorously.