Approximate real surface velocity modeling method and system

The invention provides an approximate real surface velocity modeling method and system, and the method comprises the steps: employing a near-surface velocity model obtained through the inversion of a first-motion wave as an initial velocity model, determining a high-speed top interface based on the initial velocity model, and calculating a corresponding surface elevation smooth surface, and enabling the surface elevation smooth surface to serve as a migration starting surface for velocity modeling and migration imaging; interpolating a near-surface velocity model in a range determined by a high-speed top interface and a surface elevation smooth surface to ensure that no velocity blank area exists in an operation range, and based on this, smoothing related velocity in the range determined after interpolation optimization to obtain an approximate real surface velocity model in depth domain velocity modeling. By adopting the method for modeling, the problem of imaging errors caused by elevation abrupt change and