Abstract: By taking the 2-step braided rectangular fabrics as an example, the place where the minimum distance between two crossing yarns locates in the fabrics is explored with the help of math and diagram after yarns’ moving regulation and curvilinear state are studied; Then the determination of minimum pitch length is discussed on the understanding that yarns only keep touching not interfering with each others in compacted state. A simulation model of braided fabrics is also presented on 3DS MAX platform in which braiding yarns appear straight inside the fabrics, bending at the surface with a circular cross-section. The model expresses fabrics appearance and yarns interlacing clearly, and prepares the ground for analysis of braid microstructure and related mechanics.