The invention provides a complex fault block velocity-varied structure mapping method in late development. The method comprises steps: 1, the interval velocity of a single well is acquired through a seismic interpretation horizon and a geological stratification; 2, horizon-oriented seismic attributes which can reflect lithological changes are extracted, and an attribute image and an equal T0 imageare superposed; 3, based on the principle of a consistent formation velocity at the same lithology and at the same time, velocity points of areas with no wells or with nonuniformly-distributed wellsare encrypted; 4, with the seismic interpretation horizon as a trend surface and with a fault boundary as an interpolation boundary, interpolation is carried out on the interval velocity of the singlewell, and a two-dimensional interval velocity field is built; and 5, the generated two-dimensional interval velocity grid and the equal T0 grid are multiplied for time-depth conversion, and a final structure map is obtained. The method provides accurate basic guidance for the study of a remaining oil distribution law and the development of well pattern reorganization in complex fault block fine reservoir description, a guidance role is played in late development of the reservoir of the kind, the prospect of popularization and application is broad, and economic and social benefits are remarkable.