Abstract: Abstract：High-resolution carbon isotope measurements of the upper Lower Triassic Yongningzhen Formation in Yongningzhen section of Guanling in Guizhou Province in correlation with contemporaneous strata in the world demonstrate that there is a pronounced carbon isotopic excursion characterized by wide distribution and unrestricted by sedimentary environment in the late Early Triassic of Tethys. The relationships of carbon chemo-stratigraphy to lithostratigraphy, biostratigraphy, sequence stratigraphy and trace element geochemistry of the Yongningzhen Formation are discussed in this paper. It is suggested that the δ13C variability of Tethys Ocean in the late Early Triassic was affected by global sea level change, oceanic circulation and biotic recovery as well as some other factors, and that a considerable δ13C positive excursion resulted from a extensive ocean oxidation caused by significant modification of oceanic circulation and biotic recovery related to the ocean oxidation event at that time.