Abstract: During the oil and gas exploration in subsalt structures of Kuqa Depression, the time section occurs distortion and forms pseudo-structure, because of the overlying strata structural morphology and velocity structure. The pseudo-structure differs a lot from underground actual structure. The variable velocity mapping includes the establishment of structure modeling and velocity field, but the velocity field accuracy affects the accuracy of trap identification.Avelocity field, containing log information, seismic information, sedimentary facies information, structure information and stress information, etc., could better reflect the longitudinal and lateral variation of formation velocity, with its high accuracy. It offers an accurate velocity model for variable velocity mapping, corrects distortion of the time section effectively, and thus improves the accuracy of trap identification

Key words: complex structure, velocity information, velocity field, high accuracy, trap identification