Objective: In the central of Sichuan Basin, Xujiahe Formation sandstone of Upper Triassic existence a large number of authigenic chlorite, recent years, it has given more and more attention about chlorite characteristics, chemical composition, formation temperature, the relationship between chlorite and reservoirs in geology. In this paper, authigenic chlorite is the research object, On the basis of detailed geological survey, through the method of electron microprobe, scanning electron microscopy, X-diffraction to Identify chlorite characteristics and chemical composition. Methods：Using X-ray diffraction to determine the content of chlorite, The test conditions is Cu target, voltage 35kV, current 15mA. Using electron microprobe to analysis chemical composition of the authigenic chlorite, the equipment is JEOLJXA-8800M type electronic probe instrument, working conditions are: accelerating voltage 15kV, probe current 10mA, beam spot diameter<1μm. Using scanning electron microscope to see chlorite crystal. Results：Xujiahe formation authigenic chlorite contains chlorophaeite aphrosiderite and Fe—Mg chlorite, With the burial depth from shallow to deep, chlorite species change from chlorophaeite to Fe—Mg chlorite, The temperatures calculated by authigenic chlorite have a good relation with burial depth(from 157 to 231℃). Thus it is estimated that the temperature gradient of the area is 34℃/km, the results show great consistent with the previous study paleogeotemperature dates, so paleogeotemperature calculating from chlorite is credible. Conclusions：The paleotemperature is much higher than current temperature in this area, high paleogeotemperature promote chemical densification effect, while it is more easier changed Solid type III cheese to gaseous hydrocarbons, like CH4.There are a large number of oil and gas fields in the area, high paleotemperature should be an important factor to its formation.