A set of rich-alkaline and alkaline intrusive complexes occur in Beishan-Alxa region, Northwest China. There exist such types of rocks as syenite, quartz syenite, aegirine-augite syenite, nepheline syenites, monzonite, quartz monzonites, alkaline gabbro, alkaline-feldspar granites and alkaline granite.The distribution, formation time, modes of occurrence, associations and petrochemistry of these complexes are summed up in this paper. Formed in Permian to Triassic, these complexes stretch in east-west direction, they are rich_alkaline to alkaline in petrochemistry, making up a belt of rich-alkaline-alkaline rocks and serving as a part of the gigantic alkaline rock belt along the northern border and the neighboring area of the North China-Tarim platform.