This paper has discussed the problem of the fusion of the multi-spectral and panchromatic remote sensing images, studied the fusion method based on the IHS transform and Wavelet Packet Transform, and put forward the fusion method based on the IHS transform and Best Tree Transform. First, the multi-spectral remote sensing image is transformed with the IHS transform. Second, the panchromatic image and the I component of the multi-spectral image are transformed with the Wavelet Packet and the Best Tree Transform and then merged. At last, the merged image is obtained by inverse IHS Transform. The fusion image is fairly clear in vision and at the same time makes the entropy greatest.