Tearing properties of textiles has drawn much attention due to recent applications to bullet-proof or explosion-proof vests. However, the tearing process is very complex, which is influenced by bulk material and geometrical factors as well, and there is no a matured theory for the tearing process, which limits optimal design of the textiles. Despite many experimental studies, we still lack fully understanding of the tearing process. In this paper, tearing properties of textiles with Steiner tree structure are studied experimentally and theoretically in order to develop a reliable mathematical model. The theoretical analysis elucidates that cell size and the cell's material in a structure cell of Steiner tree are the two main factors affecting the tearing properties, which are verified experimentally. The theoretical prediction of tearing strength will be greatly benefit for geometrical structure design for textile materials in the future.