Abstract: As the study and calculation on the ancient thickness of sedimentary sequences used to be based on the data of drilling wells and loggings, the application of the calculation is limited by the number of drilling wells. In this paper, the density logging data is applied combining with the thickness estimated from seismic wave velocity and the percentage parameter of sandstones in order to get the ancient thickness of sedimentary sequences in various stages and levels throughout basins. In particular, the introduction of sandstone percentage makes it possible to calculate the ancient thickness of mixed and intermediate types of strata in the basins.