Mesozoic intrusive rocks and volcanic rocks are widely distributed in Yuexi area, North Dabie orogenic belt. Zircon U Pb dating were carried out using LA ICP MS method for fourteen samples, resulting a forming age of 134~125 Ma. These rocks can be divided into two stages by 130 Ma. The first stage magmatic rocks (> 130 Ma) mainly consist of quartz diorite, quartz monzodiorite and porphyritic monzogranites; while the second stage ones (< 130 Ma) are mostly monzogranites, K feldspar granites and dyke rocks. The inherited zircons ages in the first stage rocks are made up of Middle Paleoproterozoic (1900~2120 Ma), Neoproterozoic (670~800 Ma), and Triassic; while the second stage rocks are short of inherited zircons of Middle Paleoproterozoic, and have an inherited zircon age composition of Neoproterozoic, Triassic and 140~160 Ma. Combined the inherited zircon ages composition with the character that magmatic rocks with geochemical features of high Sr, low Y occur only at the early stage, we conclude that the early stage rocks were originated from thickened lower crust, and delamination of the lower crust and thinning of lithosphere happened at ~130 Ma; while the late stage rocks results from anatexis of middle to lower crust aged of Neoproterozoic at an after thinning background.