A new enhancement method of image based on pulse coupled neural network(PCNN) and Otsu was proposed,in which PCNN is used to remove the noise after PCNN is improved and Otsu is used to search best gray threshold value for image enhancement.The results of experiments show the algorithm can remove noises more effectively than traditional method(PSNR is 18.9305 for the proposed algorithm,5.4087 for gauss algorithm),and the best threshold can also be achieved,In additional,different gray switch function is taken on the basis of the best threshold.Consequently,the remarkable effect of image enhancement is gained.