Having studied in detail the primary rock-forming minerals, metallic min- erals and petrological features of the Xin Jie layered basic and ultrabasic rocks, the authors suggest that the rocks may have been formed by crystalli- zation from a liquated magma ixe different compositions after having undergone gravitative and liquid differentiations. The main evidences are, (1)The contents of Mg，Cr, and Ni ire silicates, in oxides of iron and titanium, and in pico- tites, all increase along with the basicity of the layered rocks. This is obvi- ously related to the concentration and distribution of Mg, Cr and Ni in the liquated magma] (2)The chemical composition and the mineralogical assem- blages of sulphides change regularly with the basicity of host rock. The rela- tively high content of Ni and the very low oxidizing potential of sulphur in sulphides from ultrabasic rocks indicate that they might have been formed from a ultrabasic liquated magma relatively rich in Ni and poor in oxygen, whereas the relatively low content of Ni and the rather high oxidizing potential of sulphur in sulphides from basic rocks reveal that they might have been formed from a basic liquated magma with relatively high fugacity of oxygen and poor in Nis (3)The studies of the paragenesis of the primary rock-forming minerals and the composition of solid solution, as well as the synthetic analysis of the textures and the mechanism of the formation of fluidal and banded structures have proved that the layered rocks may have been formed by equatation at first and crystallization later.