Abstract: While searching for petroleum in petroliferous basin formed by compressional stress,much attention must be paid to the faults developed on the margin of a basin;and to the drag folds and faulting blocks which were formed due to faulting.In these areas,petroleum is likely to accumulate,and to form a petroleum field.The formation,evolution of a petroliferous basin and petroleum accumulations are closely related to faulting.For example,the petroliferous structural zones of the petroleum distributing area in Northwest China are mostly controlled by faulting.