Abstract: A method for three-dimensional velocity geological modeling with structures and velocities randomly arranged, including determining base points in three-dimensional space, building equation according to the base points to determine planar layered model, complicating a tilt layer of planar layered model, and building a fold layer model of a surface in three-dimensional space; building three-dimensional fault folded model based on the three-dimensional surface fold layer model combined with a fault plane of a random reference point and displacement of each point in a global coordinate system; building a velocity model containing a salt body based on the three-dimensional fault folded model, and simulating salt body intrusion in a geological body of a certain depth; and performing a random velocity amplitude to realize three-dimensional velocity modeling according to the layered type which has been set and according to the set velocity range and the velocity difference range between each layer of geology.