Abstract: The discovery of the marine Permian-Triassic transition bed in the Mt. Zhongliang area,Chongqing,has provided good conditions for the study of the Permian-Triassic boundary. Alternating sediments of six clayrock beds and six argillaceous limestone beds were discovered above the conventionally called Upper Permian Changxing limestone and at the base of the Lower Triassic Feixianguan shale.210 pieces of animal fossils were collected from the sequence.On identification,fossils in Nos.2—10 beds are all elements of the Late Permian Changxingian stage,e.g. Palaeofusma,Pseubophillipsia and Tetracorallia as well as large amount of brachiopods.Nos.11—14 beds are transition beds,yielding fossils such as Permian brachiopods Crurithyris and Orthotetina and Early Triassic bivalves Claraia, pteria ussurica variabilis and Eumorphotis.They form a mixed fauna. The mixture of the fossils shows that the stratigraphic section is successive. Considering that the appearance of new biotic elements is taken as the begin- ning of a new epoch,the authors propose that the Permian-Triassic boundary be placed at the base of the transition bed,i.e.the base of Bed No.11.