Abstract: Tensor product wavelet and its lifting wavelet only emphasize the horizontal and vertical edges of images. This makes the spatial resolution of the fused image lower when these two kinds of wavelet are applied to multi-focus image fusion. The image fusion method based on twodimensional four-channel non-separable wavelet has high spatial resolution, but the computation amount of this fusion method is higher since the convolution operation is adopted while the images are decomposed and reconstructed. To solve these problems, this paper lifts two- dimensional four-channel nonseparable wavelet filter banks and proposes a new method of multi-focus image fusion based on this lifting schema. Firstly, the polyphase matrix of the two-dimensional four-channel non-separable wavelet transform is factorized into the lifting format and the multi-resolution analysis of the original images is performed. Secondly, the low frequency subimages and high frequency sub-images are fused respectively. Finally, the inverse transform of the lifting wavelet is implemented and the fused image is obtained. The fusion performance is evaluated by entropy, average gradient and image definition. The experimental results show that the proposed fusion method has higher definition and spatial resolution than that of the tensor product wavelet method, tensor product lifting wavelet method, and contourlet fusion method. The speed of the proposed fusion method has been greatly improved than that of its original two-dimensional four-channel non-separable wavelet fusion method.