Thermodynamics of the Anti-de Sitter (AdS) black holes have been attracting more and more attention in the development of holographic gauge/gravity duality,because they help us understand the nature of quantum gravity.Recently,by treating the cosmological constant as the pressure of the black hole thermal system [1-4],the study of black hole thermodynamic has been extended into a general case.Please see ref.[5] and therein for in-depth reviews.