By a simple hydrothermal process, we have synthesized lanthanum oxide nanoneedles, nanorods, and nanorod bundles. The porosity of the obtained materials was found. The structure and morphology of the maintained products were studied by XRD, TG/DTA, TEM, and SAED. The porosity was illustrated by N-2 absorption-desorption, BET, and BJH curves. Moreover, the influence factors and the mechanism for the morphology control of lanthanum oxide have also been preliminarily presented.