Olivine and enstatite collected from harzburgite at the bottom of ophiolite in eastern Dngqn are rich in Mg (Fo= 91.3- 92.2, ave. 91.9; En= 87.9- 92.4, ave. 90.5). MgO content of both ol and opx is similar to that of most ophiolites in the world, but is higher than that of the abyssal peridotite, indicating that the source materials are likely to be very refractory. The Cr/(Cr+Al) ratios of spinel from harzburgite range from 0.56 to 0.66, which are also higher than those of abyssal peridotite (lower than 0.6), suggesting higher degree of partial melting for harzburgite from Dngqn. In cumulate ultramafic rocks, olivine is absent, whereas orthopyroxene (bronzite) is dominant. Bronzite has higher MgO content in comparison with other types of ophiolite and is associated with both Ca-rich plagioclase and quartz, implying that the primary magma might be boninitic magma rich in SiO2, MgO and poor in TiO2, Na2O as compared with MORB. Experiments show that the associations of both Opx+ Pl and Opx + Cpx + Pl seen to have features of high pressure reaction relative to those of plutonic rocks (cumulate or non-cumulate) beneath mid-oceanic ridge. Mineralogical study suggests that ophiolite and boninite in Dngqn are genetically related to each other. The Dngqn ophiolite represents part of plutonic rocks related to boninite and occurs probably on the bottom of intraoceanic island arc, similar to things in the island arcs of western pacific ocean.