In this paper, the Late-Jurassic basalt-andesite from Hatumohe Western Mount of Inner Mongolia are studies in the petrology, the mineral chemistry and the geochemistry of the rare carth elements. On the basis of the data, the basaltandesite may be incorporated into high-aluminium basalt series and is rich in silica, alkali, LREE, and poor in Fe The clinopyroxene phenocryst was crystallized under the low pressure condition. The basalt-andesite magma was derived from partical melting of upper mantle. The cyclothemic formation of amygdaloidal (base) and massive (top) basalt andesite is formed to be depended on the variety of oxygen fugacity and volatile component.