We construct a realization of the elliptic quantum algebra U q,p ( sl N ) for any given level k in terms of free boson fields and their twisted partners. It can be considered as the elliptic deformation of the Wakimoto realization of the quantum affine algebra U q ( sl N ). We also construct a family of screening currents, which commute with the currents of U q,p ( sl N ) up to total q-differences. And we give explicit twisted expressions for the type I and type II vertex operators of U q,p ( sl N ) by twisting the known results of the type I vertex operators of the quantum affine algebra U q ( sl N ) and the new results of the type II vertex operators of U q ( sl N ) we obtained in this paper.