Abstract: As faulting plays an important role in hydrocarbon migration and accumulation, the fine degree of fault identification affects the characterization of reservoirs and traps. In Zhangchang area of Biyang sag, the faults are characterized by complexity and the great difficulties on the plane combination and on the description of low-level sequence faults, especially the NW ones, which are difficult to identify by conventional techniques. In order to improve the accuracy of fault description and solve the rationality of fault plane combination, the seismic maximum likelihood attribute was used to study the fault distribution in Zhangchang area, including the characteristic analysis of fault seismic response, the enhancement of fault imaging technology and the calculation of maximum likelihood attribute, which solved the problem of fault description in this area. The reliability of prediction results is verified through drilling practice.