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Although some giant gas fields found in the deep-water area of the Qingdongnan Basin, China, are often associated with mud diapirs and/or gas chimneys, no comprehensive 3D work has been undertaken to characterize them. We conducted 3D seismic investigation using root mean squares (RMS), coherence, and instantaneous frequency attributes to provide better understanding of the conduit systems in the Qiongdongnan Basin. The results show that the conduit system that we investigated can be separated vertically into four zones in the following order. (1) A structurally diapiric weak zone at the base, followed by (2) an injected or reinjected sandstones zone, (3) a gas chimney zone, and (4) a mud volcanic zone at the top. The morphology of the structurally weak zone is elliptical, formed by the intersection of NW–SE– and nearly E–W–trending tectonic faults. We infer that this zone provides pathways for the ascent of the diapiric mud that was probably sourced by the underlying overpressured mudstones. The injected or reinjected sandstones zone is characterized by high amplitude anomalies (HAAs), and was probably fed by the lobes of underlying submarine fans. The gas chimney zone which is characterized by low frequencies and weak amplitudes, is probably composed of a mixture of uprising mud and free gas formed from the underlying overpressured mudstones; whereas, the mud volcano which has a Christmas-tree pattern, and composed of a central crater, the southern flank of which is a mudflow, formed when the uprising mud migrating upward through faults got to the paleo sea floor. Finally, we have proposed schematic illustrations that would aid in understanding the different stages of the formation and internal architecture of this conduit system.