Abstract: Velocity plays a critical role in seismic exploration, and accurate velocity model is an essential element for multiple removal, migration imaging and seismic inversion. In order to obtain an efficient and accurate velocity model, experiments were carried out for initial model, horizon constraint and manual velocity picking up using the two-dimensional seismic data from a suspected gas-bearing region. This paper discusses the key points and effects of non-linear tomograph for time imaging with practical data. Results show that, Without manual velocity picking, the non-linear tomograph in time domain can realize the accurate inversion of shallow formation velocity, furthermore, abnormal velocity in the shallow strata will be distinguished efficiently and accurately. Stratigraphic constraints can improve the efficiency and accuracy of velocity modeling. In the region with complex stratigraphic architecture, manual velocity picking is beneficial to the modeling of fine velocity in time domain.