Abstract: Yueshan ore field is a typical skarn-hydrothermal type of Cu(Fe)，Au polymetallic ore field in the mineralisation belt of the Middle and Lower reaches of the Yangtze River area . Copper-gold deposits in this ore field have close relationship with the Yueshan intrusion The intrusion consists of diorites. quartz diorites and quartz monzonitic diorites. The geological and geochemical characteristics，especially the petrochemistry，REE，trace elements and Pb，Sr，Nd，O isotope geochemistry of this intrusion， as well as geochemical modeling of its petrogenetic Process, are discussed. The results show that the Yueshan intrusion is a MC-type granite with 70% of mantle-derived material an d 30% of crust. derived materia1. It was formed by the process of combined wall-rock assimilation of the crustal material and fractional crystallization of the mantle-derived alkaline basalt. An open magnetic system of the Yueshma dioritic body is essential to formation an d evolution for the ore-forming fluid of the metallic ore deposits in this field.