<p>The composition and sedimentary controlling effect of the coal measure gas-bearing (CMG) system of the Jurassic Xishanyao Formation in the southern margin of the Junggar Basin (SJB) are analysed based on core observations, sample tests, and logging data. The results show that the lithological associations of the SJB can be classified into 6 types based on sediment supply strengths and sealing abilities, while the gas shows of CMG reservoirs vary greatly among different lithological associations. Due to the diversified coal-forming environment and multistage coal accumulation, superimposed CMG systems are generally developed in the SJB, and their types include: superimposed unattached CMG systems, multilayer unified CMG systems, and superimposed mixed CMG systems. Furthermore, sedimentary controls on the vertical and regional distributions of different types of CMG systems are discussed according to the sedimentary facies of single wells and well cross-sections and the corresponding data of well log, gas logging, and gas contents. Shore shallow lake environments in the Fukang, Miquan, and northern Liuhuanggou areas were favourable for forming superimposed unattached CMG systems. Braided river environments in the Houxia and the southern Liuhuanggou areas usually formed multilayer unified CMG systems. Braided river delta environments in the Manasi, Hutubi, and eastern Sikeshu areas generally developed multilayer unified CMG systems and superimposed mixed CMG systems. For different types of superimposed CMG systems, the number of gas-bearing units, coal seam gas content, vertical hydraulic connectivity and lateral continuity vary considerably, which makes it necessary to tailor the CMG co-production plan to the type of CMG system.</p>