In order to study the chemical constitutes and forming process of irreversible sediment in green tea concentrate, the main chemical components and the forming of irreversible and reversible sediment at different storage periods (0~20 d, 20~180 d, 180~250 d) under low-temperature conditions were studied and compared. The results showed that irreversible sediment contained large amounts of mineral elements and oxalic ion, while reversible sediment was comprised of polyphenols, carbohydrates, caffeine, protein and flavones. Most of sediment in green tea concentrate was reversible tea sediment. During storage of green tea concentrate, sediment contents increased, and most of the reversible and irreversible tea sediment were formed during 0~20 d. Elements as Mg, Mn, Ga, Ni and Zn mainly were participated in the formation of irreversible sediment during 0~20 d, Fe and Cu were during 20~250 d, and Al and Ca were during 180~250 d. In addition, the combination of ellagic acid and protein were also confirmed to form irreversible sediment. This research revealed that irreversible sediment was mainly composed by insoluble oxalates.