Abstract: Ultra-WideBand Multi-Input-Multi-Output (UWB MIMO) radar plays more and more important role in through-the-wall application presently, because of its well resolution performance, limited elements requirements and efficient ability for data capturing. However, since its characteristics and increased requirements, it put forward new demands for the corresponding channel construction. This study reconstruct the channel for UWB MIMO through-the-wall radar, following analyzed its characteristics. This study extend the scene form the conventional single-wall-based to building-based. Then this study compute the signal distance of each echo component and derive echo expression based on extended theory. Based on the proposed model, an efficient moving target imaging method is proposed in this paper. Using the TWI equipment in actual environment, the accuracy of the model is validated and the efficient performance in improving image quality is also demonstrated.