Display omitted •The ore-forming fugacities are first discussed in the middle belt of Xiaoqinling gold field.•The mineral paragenesis is used to constrain physicochemical conditions of mineralization.•The ore-forming environment is relative oxidation in the early of main mineralization stage. The Jinqu Au deposit, located in central Xiaoqinling gold field along the North China Craton’s southern margin, has total reserve of 21 t of Au with 4.23 g/t Au on average. It consists cccmainly of ore-bearing auriferous quartz veins in amphibolite facies metamorphic rocks of the Archean Taihua Group. The deposit’s mineral paragenesis and ore-forming processes have never been studied. This paper reports its mineral paragenesis, which includes sulfides (pyrite, galena, chalcopyrite, pyrrhotite, sphalerite, molybdenite and bornite), oxides (rutile, scheelite, hematite, magnetite), tellurides (sylvanite (Au, Ag)2Te4, hessite Ag2Te, petzite Ag3AuTe2, krennerite Au3AgTe8, calaverite AuTe2, stützite Ag5−xTe3, empressite AgTe, rucklidgeite (Pb, Bi)3Te4, altaite PbTe, volynskite AgBiTe2, tetradymite Bi2Te2S, lingbaoite (AgTe3) and melonite NiTe2) and native elements (tellurium and gold). Based on our data, the associated ore-forming processes can be deduced as: iron oxides → (CO2(g) and H2S(g) loss, ƒTe2/ƒS2 ratio increase) sulfides, Au-Ag-tellurides → (condensation of H2Te vapor) Pb-Bi-tellurides → (mixing with meteoric water) carbonate. It has been indicated by thermodynamic modelling that formation of Au-Ag-Te-bearing minerals occurred under physico-chemical conditions of logƒTe2 values from −7.28 to −3.21, logƒO2 values from −26.67 to −26.44, logƒH2S values from −1.34 to 0.34, logƒS2 values from −9.53 to −5.64, logαAu+(aq)/αAg+(aq) values from −4.72 to −4.55 and pH values from 3.33 to 4.20 at 365 ℃ and logƒTe2 values from −10.53 to −6.62, logƒO2 values from −31.99 to −30.98, logƒH2S values from −0.65 to −0.36, logƒS2 values from −13.62 to −7.20, logαAu+(aq)/αAg+(aq) values from −6.42 to −6.21 at 335 ℃. The changes in physico-chemical conditions and in precipitation of Au-Ag-Te-bearing minerals were due to boiling or to condensation of Te-rich magmatic gas into ore-forming fluids. These reflect evolution from an early oxidizing to a later relatively reducing mineralization environment. Therefore, compared with the Dahu Au-Mo deposit and with the Yangzhaiyu Au deposit, which exist in the southern and northern parts of the Xiaoqinling region, respectively, the ore paragenesis and ore-forming physico-chemical conditions of the Jinqu Au deposit were different such that its characteristics are similar to low-sulfidation Au deposits.