The present invention discloses a zoom lens assembly with capability of assuring concentricity of at least a lens group even during activity. The zoom lens assembly includes a plurality of optical lenses, at least two internal barrels, a lens holder and an alignment element wherein the lenses can be divided into at least two lens groups. The two internal barrels are used to respectively retain corresponding lens group therein to define a first and second lens sets. The lens holder is utilized to accommodate the first and second lens set therein. After twice alignment procedures in an assembled method, an internal barrel retained with one lens group is accommodated within the other internal barrel retained with another lens group to be precisely coupled. The two lens sets with mating structures are coupled to a guiding groove defined on the lens holder thereby the lens sets can slide inside the lens holder.