Abstract: The molecular structures and electronic structures of bisphenol A and B are studied by the density functional method B3LYP with 6－311++G(d,p) basis set.Through the analysis of the geometric structure,bond order,specturm and atomic charge opulation,which are consistent with the Frontier molecular orbital theory knowledge,the author explores the stability and the reactivity of bisphenol A,and that was analogy with bisphenol B.Many different methods are used to search the thermodynamic properties about the two molecules,and many thermodynamics property parameters at the different temperature are found.