Abstract: There are various structural styles in the Zengmu basin of the Nansha sea area. This paper discusses hydrocarbon accumulation and trap-related, typical structural styles. Three structural styles in the basin may be distinguished, i.e. extensional structural style (including fault block structure and listric structure), compressive structural style (including folds, thrusts and diapiric structure), and strike-slip structural style (including efflorescent structure), according to the mechanical properties of structural movements in the basin. Analysis of the characteristics of the typical structural styles indicates that local structures capable of capturing and trapping hydrocarbon can be formed in most structures of the structural styles, while sediments filling in a part of them are favorable for the formation of hydrocarbon besides that they can form traps. Because these structural styles formed earlier than the hydrocarbon-generating period of source rocks and period of large-scale hydrocarbon expulsion, they are very liable to capturing petroleum and become favorable petroleum accumulation zones and effective petroleum traps.