Abstract: Exemplified by the Devonian strata in northern Xinjiang, the present paper discusses the characteristics of sedimentary facies and palaeogeography of geosynclinal areas according to the strati-graphic, sedimentary, palaeontological and structural characteristics and sedimentary facies and palaeogeographic mapping. The theory and method of plate-tectonic sedimentology are thought to be a useful tool for the study of sedimentary facies and palaeogeography. Plate-tectonic sedimentology comprises plate tectonics, sedimentology and stratigraphy. Based on the regional stratigraphic analysis and backed by the global changes, it focuses mainly on geological characteristics, formation, development and evolution of the continental margin deposits by means of integrating exegenic processes with endogenic volcanism, intraplate processes with periplate processes and event sedimentation with normal sedimentation. Its philosophical thought is that the present is the key to the past, and that the past is the key to the past and that the past is the key to the present as well as that the celestial body is the key to the earth, and that the earth is the key to the celestial body. Its technical line is regional stratigraphic analysis→sedimentary dynamic analysis→facies dynamic analysis→sequence stratigraphic analysis→palaeogeographic analysis.