Abstract: In order to improve the image quality of images and degrade the effect of uneven illumination ambient noise in the identity recognition based on finger knuckle print，it is necessary to enhance the image in the process of image preprocessing． A new method of finger knuckle print image enhancement is proposed based on guided image filtering，due to abundant texture features of finger knuckle print image． And effectiveness is validated through the experiment in the database of finger knuckle print． The results show that the effect of uneven illumination can be avoided and details of texture can be highlighted by using the method of image enhancement．Conclusions were given by quantitative study，and more detail information are preserved after the imageenhancement，which contribute to the accuracy of subsequent feature extraction and identification．

Key words: finger knuckle print, information entropy, image enhancement, guided image filtering