Abstract: The Devonian is divided into 18 third-order sequences, in which D1, D2, and D3 include 7, 5 and 6 third-order sequences, respectively, each having the average 2.87 MPa duration, in Nanpanjiang Sag. According to boundary characteristic, these third-order sequences, which are composed of 2 supersequences (second-order sequence), are classified into 10 I-type and 8 II-type sequences. Although the Devonian being all in basin interior, lower 1st-4th or upper 17th-18th sequences were eroded near the edge of successive ancient land or on the depositional high with shallow water. The erosion number increases from the Qinfang trough in the south to Youjiang in the middle and the southern margin of the upper Yangtze land in the north. Two neritic marine subbasins included terrigenous clastic were developed on Liupanshui-Nandan and Qujing-Kaiyuan areas, fluvial-lake environment along Qujing-Yiliang, bathymetric trough on Qinfang in LST during SS1.The Nanpanjiang Sag became alternated platform and basin during TST. It was delta environment, seashore and neritic environment, carbonate tide flat-lagoon environment on the edge and mixed platform, basin environment in the interior with more differential palaeogeographic environment during HST. It developed carbonate platform on Diandongbei and Qianzhongnan area, alternated platform and basin with reef and fore-reef talus on Guangxi, intracontinental rift basin in Qingfang during SS2. In the late SS2, it became more extensive restricted platform on Diandongbei and Qianzhongnan areas.

Key words: Nanpanjiang sag, Devonian, sequence, system tract, palaeogeographic environment