Discovery of the Yaojialing super-large Cu-Pb-Zn polymetallic ore deposit was a major breakthrough in recent prospecting exploration history of Tongling area. The ore-forming parent rock was Yaojialing intrusion. However, there is no systematic study for its age and petrogenesis. Our work shows that the formation age of the Yaojialing intrusion is 140.7±1.3 Ma,belonging to the first-stage of the three stages of the Late Mesozoic magmatisms in the Middle and Lower Yangtze River Belt. Yaojialing intrusion has characteristics of enriched Sr-Nd isotopes and continental arc-like trace element patterns,which are consistent with other Mesozoic intrusions in Tongling area. This magmaitc rock was most likely formed by magma mixing derived from an enriched mantle source metasomatised in subduction processes and the Archean LCC,respectively. Magma mixture underwent fractional crystallisation of hornblende and titanite. The magmatic rocks of the first-stage were formed under a transition petrotectonic setting from extrusion to extension.