Abstract: There are four main opinions about the boundary of the permian-triassic system.The authors adopt the views of the punctuated equilbrium and event stratigraphy,on the basis of the discovery of the plane of unconfirmity,through the correlation of assemblage and evolution of palaeon-tological fossils,of structural environment of sedimentary basins and of the evolution of the sedimentary formations in the overlying strata and underlying ones of the plane of unconfirmity and then suggest that the plane of uncofirmity,is the boundary of the event,and also of thepermian、triassic system.