Abstract: This paper presents LA-ICP-MS zircon U-Pb dating and zircon in-situ Hf isotopic analytical results for the Muzidian fine-grained monzogranite dyke in northern Dabie orogenic belt. The dating results show that the granite was formed at 128.9±0.7Ma in Early Cretaceous. Two Paleoproterozoic and Neoproterozoic inherited zircons were found in the granites. The Hf isotopic analytical results show that the zircons ε_Hf(t) values are from -25.1 to -19.2 with the mean of -22.7, and the two-stage Hf model ages (T_DM2) generally range from 2115Ma to 2505Ma. The ε_Hf(t) values of the two inherited zircons are -10.5 and 6.5, with the corresponding T_DM2 of 1151Ma and 1709Ma, respectively. The zircon U-Pb dating and in-situ Hf isotopic results indicate that the parental magmas of Muzidian finegrained monzogranite dyke were derived from partial melting of Paleoproterozoic crustal rocks, with some Mesoproterozoic mantle and Archean crustal materials probably making contributions to the source. The Muzidian finegrained monzogranite dyke is considered to have been formed at the time of tectonic transition from compression to extension during Early Cretaceous in the Dabie orogen.