The Huanggang intrusive complex in northern Tongbai area of nortern Qin ling was formed in Early Paleozoic. It mainly consists of ultrabasic, basic, intermedia te and acid rocks, dominated by intermediate and basic rocks. Geochemical charact eristics of major and trace elements suggest that the complex was derived from t he fractional crystallization of cosource magma. Isotope anylisis shows the ma gma was mixed with larger amount of crustal substance. The complex was formed in islandarc tectonic environment and similar to the one formed in the setting of ocean plate subduction and was closely related to the northward subduction of th e Erlangping backarc basin. The mixed crustal substance is the product of the recycling of crustal sediments on the subducted slab.