This paper describes a method to detect glasses? frames for robust facial image processing. This method makes use of the 3D features obtained by a trinocular stereo vision system. The glasses frame detection is base on a fact that the rims of a pair of glasses lie on the same plane in 3D space. We use a 3D Hough transform to obtain a plane in which 3D features are concentrated. Then, based on the obtained 3D plane and with some geometry constraint, we can detect a group of 3D features belonging to the frame of the glasses. Using this approach, we can separate the 3D features of a glasses frame from the ones of facial features. The characteristic of this approach is that it does not require any prior knowledge about the face pose, the eyes positions, and the shape of the glasses.