In this paper, the authors attempted to characterize its origin by examining the geochemistry of platinum group elements(PGE), major elements and rare earth elements (REE) of the harzburgites which are the main rocks of the rock mass. The features are consistent with the opinion that the Dongbo ultramafic rocks were formed by the interaction of depleted residual mantle rocks with melts/fluids which were enriched with incompatible elements and PGE, especially IPGE relative to PPGE. The authors infer that the melts/fluids that reacted with the residual mantle rocks probably originated from the magmas produced in a subduction-related tectonic setting.