Varying degree of velocity anomalies has been appeared in Shijiutuo uplift in Bohai Sea,which is mainly demonstrated in the inconsistent between seismic interpretation and the actual drilling depth.In this paper, QHD33-1S area is taken as the example.First of all,the main reason that causes the velocity anomaly phenomena is the effect of sand-formation ratio by forward model analysis,and then technical approaches to improve the accuracy of the velocity field and the degree of understanding of anomalies are further explored,resulting in more precise determination of horizontal variation trend of the velocity in QHD33-1S area.Consequences of actual applications indicate that through the accurate analysis of the velocity anomaly,we can not only realize the fine description of low-amplitude structure,but also the effective prediction of the hydrocarbon-bearing properties of the reservoir.Meanwhile,the results also have a certain significance for the other low-amplitude structures in Bohai Sea. Varying degree of velocity anomalies has been occurred in Shijiutuo uplift in Bohai Sea, which is mainly demonstrated in the inconsistent between seismic interpretation and the actual drilling depth. In this paper, QHD33-1S area is taken as the example. First of all, the main reason that causes the velocity anomaly phenomena is the effect of sand-formation ratio by forward model analysis, and then technical approaches to improve the accuracy of the velocity field and the degree of understanding of anomalies are further explored, resulting in more precise determination of horizontal variation trend of the velocity in QHD33-1S area. Consequences of actual applications indicate that through the accurate analysis of the velocity anomaly, we can not only realize the fine description of low-amplitude structure, but also the effective prediction of the hydrocarbon- bearing properties of the reservoir. While the results also have a certain significance for the other low-amplitude structures in Bohai Sea.