Abstract: The Neogene Xiaolongtan Formation in Maguan, Yunnan is interpreted to be the lacustrine deposits. In the middle-lower part of the Formation, the seismites are recently identified by the authors for the first time. These seismites display the features of excellent outcrops, various rock types, continuous sequences and abundant fossils, and thus may be selected as an ideal locus for the examination of the seismite sequences in fault basins. The discovery of the seismites has provided not only seismic event records in Neogene fault basins but also new data for the study of palaeoseismic activity in the study area.