The mantle peridotites widely distributed along the Yarlung Zangbo River ophiolite zone are fresh rocks not subjected to serpentinization. Therefore, the observation under microscope and the whole rock chemical analysis are simple and convenient means for investigating their genesis and the mantle activity. Recent studies of abyssal peridotites show that they are not melt residues of batching or fractional melting of pyrolite directly after melt extraction of MORB. Petrological studies of peridotites from Luobusa ophiolite massif also indicate that the mantle peridotites are not simple residues of primary pyrolite either. Nevertheless, residue peridotites in Luobusa ophiolite were formed by two times of partial melting, i.e., the ultrahigh pressure silicates (octahedral spinel) from the transitional zone experienced melting and extracted MORB melt, and then the low pressure peridotites in the upper mantle were partially metlted again, thus forming residue peridotites.