Abstract: The simulation and expression of complicated faults is an essential technique in automatic generation of geological section. The researches of this paper are the basic theories and essential techniques of simulating complicated faults; and a series of approaches are proposed. Based on the practical geological exploration, data types are analyzed and normalized database is designed. The strata recovering technique is presented to simulate single fault. Based on topological relations between faults, the levels of complicated faults are divided. According to the levels, the relationships of strata and strata, strata and faults, faults and faults are determined. The geological sections can be generated automatically. In order to confirm the practical result of this method, some automatically generated sections containing complicated faults are presented.