Yidun Arc, located between Songpan-Garzê Fold Belt and Qiangtang Block, southwestern China was the result of Late Triassic large-scale subduction orogenic process. Daocheng granite and Haizishan granite are the two outcropped granites in the Yidun Arc during the Late Triassic and Cretaceous, respectively. On the basis of field investigation, this study carried out the analysis of petrology and zircon U-Pb ages for these two plutons. The results show rock-forming minerals of the two granitic plutons are mainly composed of plagioclase, K-feldspar, quartz and biotite, and the accessory minerals include zircon, sphene, magnetite and apatite. Sodic plagioclase grains and occasionally present K-feldspar and quartz indicate that the two granitic plutons belong to subsolvus granite and the formation of two plutons was related to orogenic event under water-bearing condition. The Daocheng granite has emplacement age of 217.4 Ma (Late Triassic), with εHf（t）ranging from -7.1 to -0.1, and two-stage model age（tDM2）of 1.26~1.7 Ga, indicating that the Yidun Arc and Yangtze Block may experience the same evolutionary history of continental crust during the Mesoproterozoic time. The Haizishan granite has an emplacement age of 98.3 Ma (Cretaceous) , with εHf（t）ranging from -12.1 to +2.5, and a tDM2 age of 1.0~1.93 Ga. In combination with previous studies about magmatism in the Yidun Arc, it can be concluded that the source rocks of Daocheng granite was probably derived from partial melting of the Mesoproterozoic lower crust material related to Yangtze Craton with addition of minor depleted mantle-derived magma, which was triggered by the underplating of large-scale mantle-derived magma under the syn-collisional tectonic setting following the westward subduction and closure of the Garzê-Litang paleo-ocean. The Haizishan granite was an A2-type granitic pluton resulting from post-collisional extensional tectonic setting related to arc-continent collision during Early Cretaceous. Its source rocks were also derived from Mesoproterozoic crustal material with addition of minor mantle-derived magma, but emplaced at shallow crust and experienced rapid cooling.