Abstract: The electromagnetic (EM) imaging is the image of the space and the EM characteristics of the object in the observation position, reflecting the EM wave caused by the object. The ultra-wideband passive EM imaging technology based on the EM inverse computation is to obtain the EM information in the space using the ultra-wideband passive antenna array, and to extract the EM characteristics using the information procession algorithm. Then computing the EM field distribution using the EM inverse algorithm, and displaying the three-dimensional situation of EM field and the object, and directly, wholly presenting the EM situation.