In order to solve the limitation of single mode of medical images,a multimodal m edical images fusion algorithm based on non-subsampled shearlet transtransform (NSST) and improved pulse coupled neural network (PCNN) is pr oposed.First,the source medical images are decomposed into low and high frequenc y subbands by NSST.Moreover, regional characteristics of the low frequency subband coefficients are obtained from regional energy and variance,a fusion rule based on weighted regional characteristics is adopted fo r the low frequency subband coefficients;and with the firing times and average gradient weighted me thod,the inner coefficients of the high frequency bands of medical images after decomposition a re fused,and the firing times are determined by the improved PCNN;the outer coefficients of the high frequency bands are combined by the maximal regional absolute value.F inally,the inverse NSST is used to produce the fused image.It is found through image fusion experi ment that,subjectively, the image fused by the proposed algorithm preserves marginal information of sour ce images effectively,and has better objective visual quality,objectively,fusion image of the new fusion rule is more superior in the objective evaluation index,such as mutual information (MI),edge evaluation factor (QAB/F) and structural similarity (SSIM).