Organic materials, such as textiles found in tombs of the Western Zhou Dynasty at Zhouyuan Site, are usually in bad conditions because of the alkaline soils in the Central Shaanxi Plain. The contexts of these textiles are barely discernable for archaeological studies because these materials are often not recognized. Thus, it is quite important to identify these materials and study their archaeological implications. Based on the phytolith approach, textiles excavated from tombs at Zhouyuan Site in 2017 were identified as having been made from reeds (Phragmites communis). Referring to the records in ancient literature and the locations where the textiles were found in the tombs, we presume the textiles were used as mattresses in coffins or barriers above coffins to resist soils.