In this paper, we give a complete classification of critical metrics of the volume functional on a compact manifold $M$ with boundary $partial M$ having positive isotropic curvature. We prove that for a pair $(f, kappa)$ of a nontrivial smooth function $f: M to {Bbb R}$ and a nonnegative real number $kappa$, if $(M, g)$ having positive isotropic curvature satisfies $$ Ddf - (Delta f)g - f{rm Ric} = kappa g, $$ then $(M, g)$ is isometric to a geodesic ball in ${Bbb S}^n$ when $kappa >0$, and either $M$ isometric to ${Bbb S}^n_+$, or the product $I times {Bbb S}^{n-1}$, up to finite cover when $kappa =0$.