Ophiolites of Ailaoshan belt are composed of meta peridotite, cumulate complex and basic lava, in which lherzolite is similar to primary pyrolite, and harzburgite is relic pyrolite. The gabbro diabase pyroxene basalt series and the pyroxenite gabbro diorite albite basalt picritic basalt series were formed respectively by crystallization or crystallization differentiation of tholeiitic magma and picritic basaltic magma produced by partial melting of primary tholeiite; the former is characterized by oceanic ridge basalt, whereas the latter by paraoceanic ridge basalt, both formed in an environment of mid oceanic ridge. Their formation time was not later than Early Carboniferous (C1), and the emplacement took place before the formation of Late Triassic Yiwanshui Formation (T3 y).