The Xincheng gold deposit is a typical altered rock type gold deposit in the Zhaoyuan-Laizhou gold ore belt of Jiaodong Peninsula, eastern China. Fluid inclusions in altered wall rocks and gold ores show that CO2-H2O-NaCl fluids have three main types, namely H2O-CO2, CO2-rich and aqueous inclusions. Early milky white quartz contains original H2O-CO2 inclusions. Aqueous inclusions at the late stage range from 147 ℃ to 170 ℃. D-O stable isotopes indicate that the main ore-forming fluid of the Xincheng gold deposit was the product of mixing between magmatic fluid and meteoric water, S stable isotopes further reveal that Au came from the source induced by the interaction between crustal/rock S and mantle S. Fluid immiscibility caused by change of mineralization stress possibly led to gold precipitation at Xincheng.