The Hardat Tolgoi Pb-Zn Deposit is located in the assembly belt of the North China plate and the Siberia plate, is a new medium-sized Pb-Zn deposit in the Erenhot-Dongwuqi polymetallic ore belt. This paper reports fluid evolution and metallogenic mechanism of the ore deposit by fluid inclusions measurement and stable isotopic compositions. Microthermometric study suggests that fluid inclusions the mineralization homogenization temperature is 195 ℃ to 408 ℃ with average 332.5 ℃, the salinity is 1.40 % to 11.93 %.NaCl eq. with average 4.87 %NaCl eq., and the density is 0.61 g/cm3 to 0.89 g/cm3 with average 0.72 g/cm3. There are two peak values range of homogenization temperature histogram diagram, one peak values from 230 ℃ to 250 ℃ is close related with the metallogenisis, another peak value from 350 ℃ to 370 ℃ is representing the early metallogenic fluid temperatrue. It is estimated that fluid formed under the pressure of about 13.0 Mpa and the depth of about 1.3 km. Test results of the laser Raman analyses indicate that the ore forming fluids belong to the H2O-NaCl system with little CO2. The hydrogen and oxygen compositions indicate that the ore forming fluid of the Hardat Tolgoi Pb-Zn deposit mainly derived from magmatic water mixed with meteoric water. The sulfides has a very uniform S and Pb isotopic composition, with δ34S is 4.0 ‰ to 6.1 ‰；w(206Pb)/w(204Pb) is 18.311 to 18.467，w(207Pb)/w(204Pb) is 15.590 to 15.636，w(208Pb)/w(204Pb) is 38.253 to 38.393. Both the S and Pb isotopic compositions of ore indicate that the metallogenic materal were derived from magma. All of this suggest that the Hardat Tolgoi Pb-Zn deposit is a shallow mesothermal deposit.