Abstract: Fractures as the important oil-gas accumulation spaces and migration pathways control the formation and distribution of oil and gas reservoirs. Accurate understanding of the distribution of underground fracture systems is critical for petroleum exploration and further oil and gas field development. Diffracted waves are the seismic responses of small-sized geologic discontinuities such as faults and fractures etc. According to the differences of event shapes between the diffracted wave and reflected wave on the plane wave record, and using diffracted-wave separation imaging technique based on plane wave prediction, the diffracted wave field is extracted from the seismic record and imaged separately. Thus the identification accuracy of small-sized structures is improved. The numerical model and actual application result show that the diffracted-wave separation imaging technology can characterize breakpoints more clearly, which could be guidance for fracture interpretation.