Aiming to address the problem that segmentation based face recognition is sensitive to illumination imbalance, an illumination equalization preprocessing for face image is proposed. Firstly, a set of extended test images are generated by considering the fact that the face image has symmetry. Then, the extended test face images are vectorized to concatenate a matrix, from which the illumination equalized test face image is extracted by low rank decomposition technique for the following recognition. Simulation experimental results based on AR database primarily demonstrate that the proposed method could efficiently improve the performance of detecting the bilateral symmetry occlusion of face, and thus promote recognition rate considerably.