In this paper, the authors systematically performed zircon LA-ICP-MS U-Pb dating and studied rock geochemistry for Xiadian magmatic rock body in Western Dabie orogenic belt. The study shows that the rock body has characteristics of richer silicon and higher alkali, and poor Ca, Mg and Al. The rock body is characterized by enrichment of LREE, depletion of HREE, obvious fractionation between LREE and HREE, and strong depletion of Eu. The rocks are enriched in LILE (Rb, K, Th, etc) and Pb elements, and are depleted in HFSE (Ta, Nb, Ti, etc) and Sr and Ba elements. The rock body belongs to A-type granite in rock type. LA-ICP-MS zircon U-Pb dating yielded a ²⁰⁶Pb/²³⁸U weighted average age of 130.0±1.8 Ma for Xiadian magmatic rock body, which represents the crystallization age of the rock body, suggesting the Early Cretaceous magmatism product. A-type granites of Xiadian magmatic rock were formed in a post-orogenic environment, which indicates that the Tongbai-Dabie orogenic belt entered the plate evolution stage.