Located in Zhongdian island arc belt in northwestern Yunnan Province, the Pulang superlarge porphyry copper deposit was formed in late Triassic during the westward subduction of the Ganzi-Litang ocean plate below Zhongdian microplate. The mineralized rocks of the Pulang porphyry copper deposit mainly include quartz dioritic porphyries and quartz monzonitic porphyries in a complex pluton, and economic ores are mainly preserved in the quartz monzonitic porphyries. The quartz dioritic porphyrites were intruded by later quartz monzonitic porphyries, but the two kinds of rocks display similar geochemical characteristics, such as similar REE patterns, incompatible trace element patterns and initial ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd ratios, suggesting that they were cogenetic products or were derived from similar sources. Geochemically, both kinds of rocks are akin to adakite, as evidenced by such characteristics as high Sr content (289×10^-6～1 200×10^-6), high La/Yb and Sr/Yb ratios, relatively high MgO and Mg^# (>59), depleted Y and Yb, slightly negative Eu anomalies and positive Sr anomalies. Moreover, the radiogenic Sr [0.705 60<(⁸⁷Sr/⁸⁶Sr)_i<0.705 74] and less radiogenic Nd [-2.85<εNd(t)<-2.20] isotopic characteristics, together with high Th/Y, Ba/La, Rb/Sr, and Ba/Sr trace elements ratios, imply that enriched source components were involved during the formation of the porphyries. This enriched source was probably derived from the basement of arc crust or subducted sediments, and then some mixing processes possibility occurred between adakitic magmas and melts from sediments and/or arc crustal materials. A comparison between the quartz dioritic porphyrites and quartz monzonitic porphyries suggests that the former have low SiO₂ (>61.0%) and K₂O (2.2%～4.4%), while the latter have high SiO₂ (>65.9%) and K₂O (3.5%～8.1%). Therefore, the authors hold that the Pulang porphyry copper deposit was probably related to the westward subduction of Ganzhi-Litang oceanic plate during late Triassic. At the early stage of subduction, the quartz dioritic porphyries with subduction-related origin were formed firstly, then increasing adakitic magmas of slab melting were mixed with melts from subducted sediments or arc materials, producing more acid and high oxygen fugacity adakitic magmas, which finally intruded the upper crust below Pulang and promoted the mineralization of the Pulang porphyry copper deposit at the shallow level.