East Tianshan, one of the important ore concentration belt in China, is characterized by a large number of mafic-ultramafic intrusions with magmatic Cu-Ni sulfide mineralization in a concentrated area. These small mafic-ultramafic intrusions are distributed in three groups, i.e., Baixintan, Huangshan, and Tulaergen, from west to east. The large-sized deposits mainly occur in the Huangshan intrusion group. The rocks mainly consist of olivine, bronzite, clinopyroxene, hornblende and plagioclase together with a small amount of Cr-spinel and phlogopite. Systematic and comparative studies of the mineralogy of rocks from ore-hosting mafic-ultramafic intrusions in East Tianshan were conducted in this paper. The estimated crystallization temperatures based on Cr-spinel and olivine pair from Huangshan intrusion group were from 1 143 to 1 257℃, which are slightly lower than those from Baixintan and Tulaergen groups (1 283~1 301℃). The estimated pressures show similar widths of 0.31~0.33 GPa calculated by clinopyroxene geobarometer for all the three intrusion groups. The characteristics of hydrous minerals and the fact of earlier crystallization of clinopyroxene than plagioclase indicate that the primitive magmas of the intrusions in East Tianshan were substantially hydrous. The clinopyroxenes in sulfide-bearing intrusive rocks have higher Al/Ti ratio, and the compositions of Cr-spinel and olivine crystals are within or close to the field of island arc volcanic basalts. Based on the regional tectonic evolution, the authors hold that the primitive magmas of sulfide-bearing mafic intrusions in East Tianshan were generated by partial melting of a metasomatic mantle, which was modified by slab-derived fluids associated with the previous subdction events. Mineral comparisons indicate that the ore-hosting intrusions in the Huangshan group have more orthopyroxene and andesine as well as lower Cr^# of Cr-spinel and Ca content in olivine. The new data obtained from this study, together with previous results, indicate that the higher SiO₂ and Al₂O₃ content in the parental magma of Huangshan intrusions group might have resulted from higher degree of crustal contamination, which also reduced the crystallization temperature of the magma.