Abstract: Lueyang Group sedimentary rock of the Late Paleozoic is located in the Mian-Lue-Ning triangle area, Shaanxi Province. It is mainly distributed in the east of Motianling block and Mian-Lue suture of South Qinling Mountain. According to field survey, there are differences in sedimentary environment and Prototype basin. Lueyang Group. is characterized by wide distribution, complex rock assemblage and diverse sedimentary environment. The rhythm-cyclic sedimentary sequence composed of coarse to fine clastic rocks developed in Tapo Formation can be divided into three sections. The lower section includes the coarse clastic rocks from alluvial fan of different source areas, and the ancient water direction is from south to north; the middle-upper section is characterized by the sedimentary deposits of the middle-high grained clastic rocks, which represent the delta environment. Lueyang Formation consists of carbonate platform facies and slope facies. The sedimentary action and material records represented by the Tapo Group marked the deposition events of late Paleozoic rifting and confined stabilization basin background on the east margin of the Motianling block and Mian-Lue suture. The research has great significance in the study of tectonic evolution in Mian-Lue-Ning triangle area.