  This paper is devoted to analyzing the critical phenomenon and phase
transition of quintessential Kerr-Newman-anti-de Sitter black hole in the
framework of Maxwell equal-area law. For this purpose, we first derive
thermodynamic quantities such as Hawking temperature, entropy and angular
momentum in the context of extended phase space. These quantities satisfy
Smarr-Gibbs-Dehum relation in the presence of quintessence matter. We then
discuss the critical behavior of thermodynamic quantities through two
approaches, i.e., van der Waals-like equation of state and Maxwell equal-area
law. It is found that the latter approach is more effective to analyze the
critical behavior of the complicated black holes. Using equal-area law, we also
study phase diagram in $T-S$ plane and find an isobar which shows the
coexistence region of two phases. We conclude that below the critical
temperature, black holes show a similar phase transition as that of van der
Waals fluid. Finally, we study the effects of thermal fluctuations on the
stability of this black hole.
