We present an efficient and robust system for landmark localization, segmentation and pose classification of ears from 3D profile facial range data. After defining 18 landmarks on the ear, including Triangular Fossa and Incisure Intertragica, a novel Ear Tree-structured Graph (ETG) is proposed to represent the 3D ear. We trained a flexible mixture model to locate these landmarks automatically. Afterwards, the ear region is outlined as the minimum rectangle including all landmarks. Finally, by calculating the turning angle between landmarks on the helix, the ear is classified as either a left or a right ear. To the best of our knowledge, there is no previous work on automatic landmark localization for 3D ear on 3D facial profile depth images. Experiments are conducted on University of Notre Dame Collection F and Collection J2 datasets, containing large occlusion, scale and pose variations. Results demonstrate the effectiveness of the proposed techniques.