Abstract: In this paper, several folded faults are analysed in Ningzheng and Moushan Areas, Jiangsu Province, and they can be classified into following types based on their configurations: anticlinal fault, synclinal fault and complex fault. All those faults were formed under the control of folding or continuosly folding with the mechanism of thrust-nappe structures. The principal markers of such faults are of the occurrence of nappe-outlier and nappe-inlier, abrupt turning of fault line, steep flanks at both sides of the fault with small angles at the top of anticlines. The decouples of the fault plane would easily be formed at the top of anticlinal fault during folding and the fault plane can be acted as sealing if oil/gas generation conditions are favourable. So that the top of the anti-clinal fault would be favourable for the preservation of oil/gas accumulation while the type of anticlinal fault can be a new type of oil/gas trap-structure.