Abstract: In order to study the practical structure of the orthogonal woven fabric,a weft binding orthogonal woven glass fiber fabric with 6 layer warp and 5 layer weft was produced on a rapier loom.The fabric was impregnated with polyester resin by VARI method and a composite sample was formed so as to observe the yarn shapes under microscope.In the orthogonal woven fabric,the warp and weft are nearly in straight shape and the binding weft,in the combined curve and straight line.The binding weft shape is associated with its position in the fabric,and has lesser and lesser straight part as nearing to the fabric center.Binding weft makes its confined warp tows gathering,and as a result,the rich and poor resin areas exist in the composite sample.The change of the binding weft shape also makes the fabric structure uneven.By analyzing the weaving process,it is found that the change of binding weft shape lies in its sliding in fabric forming process.From the fabric edge to the center,the binding weft′s sliding resistance gradually increases and so does its tension.