A method of MMW/IR fusion for target recognition based on gray relational analysis with adaptive weights and the DS theory is presented. Firstly, the gray relational grade of each sensor is computed and treated as the basic probability assignment function. Then, the fusion recognition result is computed by the DS theory. At the step of gray relational grade calculation, an algorithm of entropy analysis is introduced to adaptively determine each weight, and then the system performance is improved. The experimental results based on real data show that the proposed method is effective.