Abstract: Aolunhua Mo-Cu Deposit is a typical porphyry deposit.The ore bodies mainly occur in the monzonitic granite porphyry in the Early Cretaceous.The hydrothermal mineralization can be divided into 4 stages:quartz＋pyrite＋molybdenite stage(Ⅰ),quartz＋molybdenite＋pyrite＋chalcopyrite stage（Ⅱ）,quartz＋pyrite＋chalcopyrite＋sphalerite stage（Ⅲ）,quartz＋carbonate veins stage（Ⅳ）.The study on mineralogy,petrography of fluid inclusions,micro-thermometry of inclusions,and stable isotope analysis shows that the primary ore-forming fluids in Stage Ⅰ and Ⅱ are high temperature(316 ℃-462 ℃),high salinity(2.23 %-45.54 %)NaCl-H2O-CO2 type solutions;the ore-forming fluids in Stage Ⅲ are high temperature(300 ℃-368 ℃),low salinity(3.37 %-9.34 %)NaCl-H2O type solutions; the ore-forming fluids in Stage Ⅳ are low temperature(130 ℃-260 ℃),low salinity(3.53 %-11.95 %)NaCl-H2O type solutions,indicating the trend of decreasing ore-forming temperature and salinity.H,O isotope analysis shows that early ore-forming fluids are mainly magmatic water,meteoric water blended in later;δ34S value is 1.9 ‰-4.9 ‰,indicating magmatic source of S isotope.Due to decreasing temperature and pressure,the fluids boil,CO2 vaporizes,fluid pH increases,so that ore-forming elements such as Mo,Cu precipitates and eventually concentrates into deposits.