The Putuoshan pluton is a typical multi-stage I-A composite granitic complex in the coastal area of southeastern China. Zircon U_Pb dating demonstrates that it consists mainly of three stage magmatic intrusions, which are from early to late quartz diorite porphyry (≈170 Ma), biotite moyite (≈110 Ma), and miarolitic moyite (≈90 Ma). Among them, the biotite moyite, which oftencontains abundant meladioritic enclaves, forms the main body of this pluton. This paper is mainly devoted to the study of the biotite moyites (host rocks) and the meladioritic enclaves. Geochemically, the host granites are characterized by high silica and alkali contents, and show metaluminous to weakly peraluminous attribute. They are also enriched in LILE (e. g., Rb and Th) and LREE, with LREE/HREE ratios ranging from 8.58 to 13.83, and depleted in Sr, Ba, P and Ti, etc. In the chondrite-normalized REE patterns, they display moderately to strong negative europium anomalies (δEu=0.29～0.43). Integrated geochemical data suggest that the host rocks are highly fractionated I-type granites. The variation of major and trace element abundances between the host granites and the meladiorite enclaves shows the evolutionary tendency of magmatic mixing. The host granites and the meladiorite also have similar Nd isotopic compositions, with εNd(t) values being -6.30～-6.60 and -6.95～-7.12 respectively, which are all indicative of mixing of crustal and mantle materials. Based on a comprehensive analysis of their tectonic settings as well as geological and geochemical data, the authors hold that the meladiorite enclaves in the Putuoshan pluton were generated by mixing of mantle-derived basic magma and its induced crustal felsic magma in a tensile environment.