Abstract: The lack of systematic investigation into the occurrence state of gold in deep-seated ores from the Nanlü-Xinmu mining block of the Jiaojia gold deposit has hindered the efficient utilization of mineral resources. X-ray fluorescence spectrometry, chemical composition analysis, polarizing microscopy, and scanning electron microscopy-energy dispersive spectroscopy （SEM-EDS） were employed to investigate the mineral composition, gold occurrence state, and surface characteristics of gold-bearing minerals in the deep-seated ores, with emphasis on their implications for flotation interface regulation. The results show that the gold grade is 1.2−3.0 g/t. Pyrite is the dominant sulfide （67.12 %）, followed by chalcopyrite （14.15 %） and galena （4.48 %）. The major gangue minerals are quartz （25.42 %）, K-feldspar （25.19 %）, and plagioclase （18.20 %）. Gold minerals consist mainly of silver-bearing native gold （38.4 %） and electrum （38.2 %）, with silver-bearing gold minerals accounting for 82.5 % in total. Gold particles are fine-grained, with 87.8 % having a grain size below 30 μm and a mean grain size of 15.36 μm. Encapsulated gold is dominant, with pyrite-hosted and quartz-hosted inclusions constituting 66.0 % and 23.8 % of total encapsulated gold, respectively. Interfacial chemical analysis indicates that the preferential surface segregation of silver in silver-bearing gold minerals enhances xanthate collector adsorption, favoring the flotation recovery of gold-bearing sulfides. Pyrite formed at different stages of mineralization exhibits distinct surface morphologies, reflecting systematic differences in surface defects and susceptibility to oxidation. Three types of interfacial contact （inclusion, fracture-filling, and intergranular） exist between gold and host minerals, with fine-grained encapsulated gold representing the core interfacial obstacle to flotation recovery. Slime coating by layered silicate minerals such as sericite, together with sulfide surface oxidation, further reduces collector adsorption efficiency. Accordingly, a staged grinding-flotation flowsheet involving coarse grinding to recover pyrite carriers, followed by regrinding of the coarse concentrate to liberate encapsulated gold, is proposed, along with interfacial regulation measures such as pulp potential control and nanobubble-enhanced flotation. These findings provide a mineralogical and interfacial chemical basis for flotation interface regulation and optimization of mineral processing and metallurgical operations.