  In this paper, taking in to account Brans-Dick theory, we investigate
thermodynamic behavior of charged black hole solutions. We study the analogy of
the black hole solution with the Van der Waals liquid-gas system in the
extended phase space by considering the cosmological constant as dynamical
pressure. We obtain critical values of thermodynamic coordinates and plot
$P-r_{+}$ and $G-T$ diagrams to study the phase transition.
