At present, the major of the information fusion method is closely related with prior knowledge, that can not always be satisfied in real application scenario. To effectively solve this problem, the concept of support degree is proposed on the basis of exponential attenuation function. Then, two kinds of support degree based information fusion algorithms that do not require any prior knowledge are presented. Finally, the proposed algorithms are adopted to process the measurement values of three radars. The experimental result indicates that the algorithm is good in fusion result. Meanwhile, the algorithm is simple in implementation.