Abstract: In the northern Yaken of the Tarim Basin, the surface of 3d work area fluctuates obviously, making it difficult for velocity prediction. Improvements have been made with the newly-designed velocity modeling technology based on floating datum. Migrating error is avoided. The regularity of compaction velocity is used to fill the gap for velocity spectrum data in the shallow. The use of average interval velocity to calculate thickness avoids the problem of bigger average velocity. Ticking outliers based on isochronous speed sliced, the dependence on interpretation layer is avoided smoothly. The interpretation depth with the new method has a standard deviation of 123 m from well, which is 2.19% of relative error. The new-derived equation shows that a larger replacement velocity causes floating datum higher than surface. After the floating datum is compensated to the surface (long wavelength static correction,) the standard deviation decreases to 46 m and the relative error is 1.59%. The new technology implements the structure of Ykb1.