Abstract: The Bight Basin of Australia is one of the few large under-explored sedimentary basins in the world, and the Ceduna sub-basin of the Bight Basin has received high attention of oil companies in recent years. However, the stratigraphy, structural evolution and structure types of the sub-basin, constrained by the seismic data with low signal-to-noise ratio, remain unclear up to date. Based on the reprocessed 2d seismic data, regional seismic interpretation has been completed, on the basis of which, the structural evolution history of the Ceduna sub-basin was rebuilt using ‘back-stripping’ balanced sections. Duplex gravity driven decollement structure model was finally established on analogy and comparison with other passive margin basins having similar tectonic and depositional background. Further structural analysis of the Ceduna sub-basin was made to reveal the structure features. 8 types of structural traps under 3 classes were generalized and the belt of favorable traps were found, which provide the clue for future exploration in the sub-basin.