The composition of quartz inclusions and trace elements in ore indicate that gold|bearing fluid in the Xiadian gold deposit, Shandong Province, stemmed from both mantle and magma, belonging to a composite origin. Based on theoretical analysis and high temperature and high pressure experimental studies, gold|bearing fluid initiative localization mechanism and the forming environment of ore|host rocks are discussed in the present paper. The composite fluid extracted gold from rocks because of its expanding and injecting forces and flew through ore|conducive structures, leading to the breakup of rocks. The generation of ore|host faults and the precipitation of gold|bearing fluid occurred almost simultaneously. This study provides further information about the relationships between gold ore veins and basic|ultrabasic vein rocks and intermediate vein rocks, the spatial distribution of gold ore veins and the rules governing the migration of ore fluids. The composition of quartz inclusions and trace elements in ore indicate that gold | bearing fluid in the Xiadian gold deposit, Shandong Province, stemmed from both mantle and magma, belonging to a composite origin. Based on theoretical analysis and high temperature and high pressure experimental studies, gold | bearing fluid activity localization mechanism and the forming environment of ore | host rocks are discussed in the present paper. The composite fluid extracted gold from rocks because of expanding and injecting forces and flew through ore | conducive structures, leading to the breakup of rocks. The generation of ore | host faults and the precipitation of gold | bearing fluid occurred almost simultaneously. This study provides further information about the relationships between gold ore veins and basic | ultrabasic vein rocks and intermediate vein rocks, the spatial distribution of gold ore veins and the rules governing the migration of ore fluids.