Abstract: 【Objective】 To explore the changes of fruit quality during the ripening process of astringent Thompson Seedless grapes, and to provide a scientific basis for improving the economic benefits of the fruit for fresh eating. 【Methods】 The fruit sensory quality indexes and internal and external quality indexes were compared with those of normal Thompson Seedless as the control material and the fruit flavor quality was evaluated by correlation analysis and principal component analysis. 【Results】 The results showed that the fraction of soluble solids and solid-acid ratio in Thompson Seedless grapes increased, the fraction of titratable acid and soluble protein decreased, and the content of total phenols, flavonoids and tannins increased and then decreased as the fruit matured and became astringent. The correlation analysis showed that total phenols, flavonoids, tannins, vitamin C and soluble protein content were highly significantly and positively correlated with bitterness intensity, and soluble solids content of astringent Thompson Seedless grapes was positively correlated with sweetness intensity. 【Conclusion】 The astringency of Thompson Seedless grape fruit is closely related to the type and content of phenolic substances.