Abstract: In order to take in-depth research of the characteristics of the main carbonate sedimentary system and a variety of micro-phase in Puguang Gasfield, and establish the regional stratigraphic framework of the Puguang gas field, we identify and classify the sequence boundary of main wells in Puguang Gasfield. Five kinds of grade Ⅲ sequence boundaries developed, such as a unconformity sequence surface of the upwarped erosion, transgressive sequence on the super-unconformity surface, subaquatic unconformity sequence surface of the interruption in deposition, unconformity sequence surface of the local exposure, and conversion interface of the lithology and the lithofacies. Four kinds of the grade Ⅳ sequence boundaries developed such as the surface of discontinuity of the lithology, conversion surface of the sedimentary facies, the surface of the positive drift of the GR value, and the surface of the alternation of the diagenic metamorphism. Lower Triassic Feixianguan Formation of Puguang 102-1 well can be divided into one grade Ⅱ sequence, two grade Ⅲ sequences and nine grade Ⅳ sequences, and some analysis was done to sequences can be used as favorable reservoir.