Abstract: This article demonstrates different transmission characteristics with different moisture rate foliage in Terahertz band via adopting the time-domain finite integral technique (TDFIT). Thereinto, the material characteristics are represented by the double dispersion model with continuous water particle distribution, and the double dispersion model has involved the impact which foliage’s moisture rate posed on electromagnetic parameter. The geometric models of foliage are represented with NURBS curve modeling, in which foliage’s surface has been roughened. The article uses the common time domain integral technique to precisely describe the petty fluctuation of foliage surface and continuous material distribution, which improves the computation accuracy and efficiency effectively. This article eventually demonstrates the validity of the electromagnetic modeling method and the computation algorithm based on the contrastive analysis of simulation results and experimental results.