Abstract: A concept of multi-complex matched filter is introduced to improve the recognition of optical correlation image and the resistance of distortion, and a new way for the recognition is discussed. The synthetic discriminant function（SDF）was combined with K-L transform as a classical concept to effectively expand the dynamic range of single matched filter. Therefore, the scale distortion was restrained and the recognition efficiency of the optical pattern recognition (OPR) system was significantly improved. The simulation indicates that the concept can increase the update speed of filtering by a factor of 5, compared with that of the ordinary filtering, in the case of the distortion of half scale. The algorithm proved valid and feasible.