Abstract: Taking the western Taiwan Strait Basin as the research subject, two large regional sections, which control the regional tectonic framework, are selected to restore balance sections using 2D Move software. The extension amount, the extensional ratio and the extensional coefficient are calculated, in addition to the preliminary calculation of structural subsidence amount of the basement for each sag in the research area. Upon the basis, the tectonic evolution process and its regional differentiation in Western Taiwan Strait Basin are quantitatively studied. The results suggest that: (1)Both extensional intensity and structural subsidence amount of basement are drastically decreased from Eocene to Miocene, indicating that Oligocene is a transitional period of tectonics; (2)There is continuous fault subsidence from Paleocene to early Eocene, differential uplifting in Middle Eocene and slow subsidence after Miocene in the research area; (3)Taiwan Strait Basin has experienced four stages of evolution i.e. fault subsidence from Paleocene to Eocene, depression in Miocene and fore-arc basin between Pliocene and Quaternary.