Abstract: A novel pixel-level remote sensing image fusion based on heat conduction equation is proposed in this paper. The main contributions of the paper are as follows: 1) the diffusion relationship between the high-resolution image and the low-resolution image are obtained in the space domain, where Brovey transform (BT) is one of its special cases; 2) a unified expression of pixel-level image fusion and image enhancement is obtained. And a brightness balanced-based image fusion is obtained by using the expression; 3) the disadvantage that the standard variance-based image fusion method will result in the loss of high spatial resolution panchromatic image information for smaller variance low-resolution multispectral images is pointed out. Experimental results show that our approach does not lose the image spatial resolution and spectral information and outperforms the existing method.