Abstract: Velocity modeling is a key technology for 3D pre-stack migration. A method of 4D data velocity analysis based on pre-stack time migration velocity scans was introduced. By velocity scans, a group of migration stack section of different velocity can be obtained, which can make up 4D data volume through the package of velocity modeling software. By iteration and correction for many times, final velocity model can be constructed and this technology can pick up Velocity function by the result of migration image to satisfy the need of pre-stack time migration for the right imaging of complicated geological structure. This technol-ogy is successfully applied to 3D pre-stack time migration processing.