Dexing copper deposit, known for rich gold, is the most typical continental porphyry deposit in the east of China. Based on systematic field observation of whole ore body and cataloging of core rock, alterationmineralization system of Dexing Tongchang porphyry coppergold deposit is clearly studid to Distinguish the order of mineral veins formation and to implement the microthermometere of fluid inclusions in the veins in this paper. According to the behavior of fluid inclusions of different mineralization stages and the result of microthermometer, the characteristics of oreforming fluid of alterationmineralization system of Dexing Tongchang porphyry coppergold deposit are completely recognized. Dexing Tongchang porphyry coppergold deposit was formed by multistages of alteration and mineralizaiton from early to the end. In the early stage, the four Atype veins were formd when the porphyry rock is not completely solidified so that the veins are irregluar or unclearly bordered with wall rock or porphyry rock and largescale of Kfeldspar alteration, biotite alteration and even magnetitization. In the middle stage, the seven Btype veins where symmetrical pectinate quartzs or chlorite are vertical to the vein wall and metal minerals are as their centerline, were largely formed when most of the ore minerals including the chalcopyrite, molybdenite, bornite and so on were formed contemporaneously. At the postminerlization stage, three Dtype veins with or without alterated Hydromica halo and the lastest hypothermal carbnatequartz veins and biotite veins were fromed when the mineralizaiton system was opened and meteoric water and undergrand water infused into the open fissure. Mineralization and alteration system of Dexing Tongchang coppergold deposit is similar to that worldwide typical porphyry deposit, showing that Atype Veins and Ksilicification occurred on the boundary between wallrock and granodiorite porphyry, B and D veins and propylitization occurred outspreading along the wallrock and granodiorite porphyry near to the boundary，and the latest carbonate, quartz and biotite veins and argillization were spliced above or out of the propylitization belt. Fluid inclusions of differt veins varied with the oreforming process that there were mainly LVH (one or moe daugther metal mineral or transparent minerals are contained in the fluid inclusions)and VL (more than 50% vaper in volume) types of inclusion in the early Atype veins, lots of LVH and VL and little of LV fluid inclusions in the Btype veins at middle stages, and VL and LV (less than or equal to 50% vaper in volume) fluid inclusions in the latest Dtype veins. The behavior fluind inclusions in the temperaturemearsuring process and the result of microthermometer have been use to evalute the conditions of different mineralization stages. In the early stage, when porphyry magma still unsolidified, the Atype veins are formed at the 600～800℃ and 120～50MPa or even above them; at the middle stage, the Btype veins are formed when the static rock pressure (55MPa) transferred to the static water pressure (20MPa); and at the latest stage, the temperature and pressure totally decrease to 350～375℃. After the mineralization of Tongchang deposit, two hydrothermal activation without mineralization overprinted on the former mineralization veins, respectively under 320～300℃ and 180～200℃. The hydrothermal fluid varied from magma fluid as A and B veins fromed to meteoric water or ground water as the Dtype veins were formed. However, there are CO2bearing fluid inclusions hosted in Dexing Tongchang coppergold deposit, which are never found in other porphyry deposits, or only little in one oreforming stage in some porphyry deposit. Thus may represents abnormal on its metallogeny of Dexing Tongchang porphyry Cu deposit.