Abstract: Based on the feasibility of using speed spectrum data for velocity study, a variety of methods are used in this paper to identify and filter the velocity spectrum data. Statistics and analysis are performed by using effective velocity spectrum data to calculate the velocity distribution in the Oujiang, Minjiang, Keelung, and Jinjiang regions and the average speed trend of the whole region has been worked out. The methodology for mapping average velocity of each reflection layer is discussed so as to provide data for basic time-depth conversion. In this paper, we also analyzed the consistency between the seismological and geological structures and their velocity trend, discussed the regional isovelocity pattern and stratigraphic distribution trend as well as density distribution in a structurally inactive basin as such. The results are helpful for study of gravity data.