The Dongqiao ophiolite, located in the northern part of the middle part of Bangong -Nujiang suture zone, is composed of mantle peridotite and chromitite, and the mantle peridotite is manily harzburgite and dunite. Chromite is mostly lenticular and banded, and often with dunite cladding, both of which occur in the harzburgite dyke. The olivine Fo values (91.2~92.9) and Cr# values (70.16~76.60) of the para-mineral chromium spinel in the mantle peridote of Dongqiao are high, which are similar to Dingqing, Qielihu and Yilashan rocks in the Banong-Nujiang suture zone, indicating that the Dongqiao ophiolite has experienced a high degree of partial melting. The chemical composition of chromium-spinel of Dongqiao chromitite indicates that there are both high chromium-type chromitite (Cr# value is 60.67~82.67, Mg# value is 54.45~68.08) and high aluminum-type chromitite (Cr# value is 56.36~59.62, Mg# value is 67.20~72.68) in the ophiolite. The REE characteristics of the mantle peridote in Dongqiao show that it has the characteristics of pre-arc mantle peridote, and the trace element partitioning pattern is very similar to that of Izu-Bonin-Mariana, indicating that the Dongqiao ophiolite may have formed in the ocean floor spreading environment of plate subduction zone. The PGE element partitioning pattern of chromite is similar to that of Lobusa chromitite, which is characterized by enrichment of IPGE and loss of PPGE. The analysis of Dongqiao mantle peridotite and its chromite equilibrium melt shows that high-chromium type chromitite was formed in SSZ type forearc basin, high-aluminum type chromitite was formed in MORB type environment, and the adjacent ophiolite of Bangong -Nujiang suture zone indicates that Dongqiao mantle peridotite and its chromitite have undergone MOR→SSZ multi-stage evolution process. In the transition zone from dunite cladding to banded disseminated chromitite, Cr# value increases (67.22~68.48) and Mg# value decreases (57.35~74.56), which reflects the existence of different degrees of partial melting in the mantle source region. It is further indicated that the mantle peridotite and its chromitite may have undergone melt-rock reaction to a certain extent.