A series of sediments-hosted vein-tpye copper deposits have been discovered in the western part of the basin. The Kedengjian vein-type copper deposit is one of these deposits in Lanping basin. The Cu mineralization mainly occurs as sulfide-bearing quartz-carbonate veins in faults and fractures, hosted by volcanic rocks of Triassic Cuiyibi Formation(T₃c). Ore-forming process of the Kedengjian copper deposit can be divided into two stages: the major stage(massive polymetallic sulfide quartz vein stage), and the late stage(carbonate-quartz stage). A detailed study of fluid inclusions led to the recognition of two types of fluid inclusions, i.e., aqueous water, and CO₂H₂O inclusions, with the aqueous water inclusions being dominant. Total homogenization temperatures range from 180℃ to 240℃, with corresponding salinities from 8% to 14% NaCl equivalent. These characteristics of fluid inclusions in the Kedengjian copper deposit are comparable with those of basinal mineralization systems, which formed most Pb-Zn deposits in the Lanping basin. The H, O isotope studies of inclusions in quartz suggest that the ore-bearing fluid was derived from atmospheric water. The δ³⁴S of sulfide minerals are widely variable between -20.8‰ and -9.4‰, indicating that the sulfur was derived from the sedimentary rocks of the basin. Comprehensive studies indicate that the ore-forming materials originated mainly from sedimentary rocks, and the ore-forming fluids were mainly composed of basinal brines, derived from formation water in strata and meteoric water.