In order to control various industrial flow fields there are two types of square lattice structure, biplane grid and woven screen. Woven screen which is used as a rectification lattice consists of the alternation of knitted circular crynders. Though the woven screen and the biplane grid have similar shape, the vortex structure behind two types of lattice is though to be different each other. However, the vortex structure formed behind these lattices is not almost known yet. It way leads to the explanation of the straightening effect of woven screen to clarify vortex structure. Therefor, the aim of this investigation is to clarify the vortex structure formed behind woven screen and the growth process in the near wake by means of flow visualization and PIV measurement using the stainless steel large model of woven screen submarged in the water tunnel flow under the low Reynolds number. As a result, two pair of longitudinal vortices behind all downstream cylinders are produced in the cross region of circulare cylinder menbers. The secondary flow which is made by four longitudinal vortices shows a plus or minus vorticity in each mesh. It becomes difficlut to confirm four longitudinal vortices in the wake region of x/d=10.0.