Abstract：Qaidam basin in northern Tibetan Plateau has preserved intact Cenozoic strata. Based on field survey of the Changweitai section along the northeast limb of the Mangya depression anticlinorium in combination with thin section analysis, the authors studied the lithology, facies and rock combination characteristics. Then through the basic sequence analysis, the cycle characteristics of each formation were revealed. Finally, the holistic sedimentary evolution characteristics of the Cenozoic strata were summarized, with the purpose of revealing the evolution of the regional Cenozoic sedimentary environment.