To explore the paleoclimate evolution of the terrestrial Permian-Triassic system,mudstone samples were collected from the Permian Shiqianfeng Formation ( P_3 s) and the Triassic Liujiagou ( T_1 l),Heshanggou ( T_1h) and Zhifang ( T_2 z) formations in the Shichuanhe section of Tongchuan ( Shaanxi Province) in the southern Ordos Basin. The samples were analyzed for their mineralogy,petrology,and geochemistry. The paleosalinity,paleoredox and paleoclimate evolution were studied by the major-trace elements,total organic carbon ( TOC),and carbon and oxygen isotopes. It is shown that the geochemical and carbon-oxygen isotope compositions near the P /T boundary had changed greatly. Fluctuation of climatic and environmental chemical indicators reflects the paleo-climatic /-environmental changes in the Ordos Basin from the Late Permian to the Middle-Late Triassic. It is shown that the Shiqianfeng Formation was deposited in a fluvial-deltaic environment that was relatively reduced,and that the paleoclimate was relatively warm and humid. The purplish-red clastic rock of the Lower Triassic Liujiagou and Heshanggou formations were deposited in shallow water,hot and arid fluvial-deltaic environment under strongly oxidizing conditions. During the deposition of the Middle-Triassic Zhifang Formation, the water level rose and chemical transfer was enhanced,and the depositional environment may have been semi-arid /-humid and reducing. Carbon isotope evidence shows that the P /T boundary in the terrestrial Ordos basin has significant negative delta~(13)C_(PDB) features,which are comparable with the global marine P /T boundary. This indicates that major geological events such as abrupt climate changes and mass extinctions were also recorded in the North China continental P /T boundary,consistent with the marine stratigraphic record.