Abstract：Combining with real situation of Bachuxia river work zone,the paper discussed in detail the 3-D velocity model-building method in that area.Taking the model-building thought of seismic velocity equilibrium as a guide and random modeling as a basis,the method uses discrete smooth interpolation technique to construct 3-D discrete space model.In comparison with other model-building methods, the model-building steps and application effects of the method has following advantages: (1) the model-building process from points to plane to cubicity fully and finely reflects 3-D discrete space structure; (2)a great amount of interpolation and numeric modeling methods are provided during model building, which ensures the model-building reliability; (3) the logging and seismic information are fully used to ensure the model-building correctness: (4)the solved velocity model can correctly reflect the changing low of velocity space.The concrete model-building steps are introduced in the paper.The application results in Bachuxia river area show that the method can better solve the velocity issue in seismic data processing and interpretation, especially in complex areas,which can provide accurate velocity data for oil/gas field exploration
