Taking full advantage of the multispectral properties of multispectral image, we should get the exceptional accurate edge. Clifford algebra is suit for dealing the multidimensional data, and can give expression to the association of the data better than the general algebra. It is a very rewarding method that to via Clifford algebra to get the edge of the multispectral image. In the paper, we discuss the base properties of Clifford algebra firstly, and then detail the Clifford algebra description of the multispectral image. Lastly the new Multispectral Image Edge Detection algorithm is proposed, which is based on the Clifford gradient. Compared the algorithm with maximal entropy edge detection algorithm in experiments, we generalize a conclusion that the new method can retain the more perfect edge information of the image.