For long ago, it is known that the 't Hooft limit of large N gauge theories is related to string theories. In 1998, Maldacena identified precisely such a relation: the so-called AdS/CFT correspondence speculates a duality between a large N strongly coupled supersymmetric and conformal Yang-Mills theory in 4 dimensions and a weakly coupled string theory defined in a 5 dimension anti-de Sitter spacetime. Nevertheless, the application of this conjecture to QCD is not straightforward, being QCD neither supersymmetric nor conformal. The AdS/QCD correspondence approach aims at identifying the dual theory of QCD. Among the different available holograhic models of QCD, I will focus on the so-called soft wall model which reproduces well established QCD features as the linear Regge trajectories of meson masses. In this talk, I will discuss the advantages and the drawbacks of this model in respect to the scalar channel.