The Xikuangshan type ferro-copper deposit is an important deposit type in the Dongchuan copper mine. Although previous researchers made detailed investigations, the origin of this kind of deposit remains controversial. In order to probe into the genesis and sources of the ore-forming materials of its ferro-copper layer, the authors analyzed the O isotopic compositions of the Xikuangshan type ferro-copper deposit and studied its isotope geochemistry. The results show that the values of δ³⁴S in sulfides (from -10.9‰ to 15.9‰, with an average of 0.455‰) can be divided into three groups: ① values between ±4‰ (15 pieces), with the characteristics of meteoritic sulfur; ② values in the range of ±(5～8)‰ (6 pieces), influenced by the volcanic sedimentation; ③ values in the range of ＞10‰ or ≤-10‰ (2 pieces), suggesting that sulfur came mainly from the rock magma (volcanic eruptions) and subordinately from seawater sulfate and stratigraphic biological sulfur. The carbon of the Xikuangshan type ferro-copper deposit has the characteristics of mantle-derived carbon, implying that mantle material participated in the ore-forming process. The δ¹⁸O_V-SMOW values of magnetite change between 1.3‰ and 9.8‰, with an average of 4.875‰. The composition characteristics of O isotope indicate that the deposit belongs to the volcanic sedimentation-exhalation deposit. The main ore-forming source came from volcanic eruption, and the metallogenesis was connected with magmatic activities, marine facies chemical sedimentation and seafloor hydrothermal solution sedimentation.