For the problem of low visibility caused by fog weather, a defogging method based on hyperspectral image unmixing technique is proposed. A physical model of the imaging sensor in fog weather is established, and the mathematical model of linear spectral mixture with fog endmember is unmixed. The fog endmember obtained from the abundance inversion is removed. The defogging image is achieved after the abundance adjustment of the remaining endmembers. Compared with the fog/cloud removal based on the single- band or full-color image, the physical meaning of this approach is clearer. From the objective evaluation, it can be seen that the defogging effect of the proposed method is good. The defogging image has richer details.