A circulating structure for a linear guideway is arranged in a circulating assembly the linear guideway. The linear guideway includes two circulating assemblies, and each circulating assembly is provided with a circulating channel. Each circulating channel is provided with a third guiding groove. A rolling element system is arranged in the circulating channel and consists of plural rolling elements and a rolling element chain. The rolling element chain includes plural spacers and a linking portion located at both sides of the plural spacers to link them with one another. The linking portion circulates along the center line of the third guiding groove, and the third guiding grooves have a constant width.