Abstract: The southern Qinling rift trough is installed between the Qinling mieroplate and Mo-tianling terrane. The stress in this article is put on the stratigraphy,sedimentology,volcan-ism and palaeobiogeography of the Devonian strata in the rift trough and Motianling ter-rane,as well as their depositional systems and basin framework. The Devonian Sanhekou Group in the rift trough consists of metamudstone,silty mudstone and thin-to thick-bed-ded lime mudstone in deep-water basin and shelf environments interstratified with tholeiite and alkali basalt. The chemical analysis and REE distribution patterns of tholeiite and al-kali basalt indicate the existance of the rift trough during Devonian time. The Devonian strata in the Motianling terrane are made up of terrigenous nearshore and shelf deposition-al system,and carbonate ramp and shelf depositional systems. The terrane is interpreted as part of the northern continental margin of the Yangtze plate.