Vitrinite reflectance(Ro) data of 6 samples is form Yanchang ground of the Late Triassic of Hancheng and Luonan area in Southeast margin of Ordos Basin，and Apatite fission track(AFT) dating is carried on 6 samples collected from this area. The Ro data and AFT show that the thermal evolution of organic in Southeastern margin of Ordos Basin is higher than in other places, Ro range is from 0.65% to 0.78% in Hancheng area, the section of Luonanjingcun in primeval basin’s south edge was influenced by intracontinental orogenesis of Mesozoic in Qinling. So, the Ro of Yanchang Group of upper Triassic, which is the higer degree of thermal evolution,which can reach 2.67%-3.71%.The AFT data shows that the value of the AFT central age decreased along with the strata growing older. The calculated each sample through thermal evolution history, the Southeast margin of the Ordos Basin has had an important structure-heat event at late Mesozoic(100Ma), These two region belong to different type of thermal evolution. Hancheng area is Buried heating type,and the Luonanjingcun section is the type control by tectonic-magmatic activities. This knowledge is consistent with the field geological evidence.