The invention provides a vehicle laser radar three-dimensional scanning method, and a terrain classification method and system. A laser emission unit, a signal detection unit, a POS unit and a core processing unit are arranged on a vehicle, wherein the laser emission unit comprises a colorful laser source, an acquisition result of the signal detection unit is inputted to the core processing unit, point cloud acquired through scanning is acquired, the colorful spectrum information of the point cloud is acquired, and the relative geometric position of the point cloud is determined; the attitude position information is further recorded by the POS unit and is inputted to the core processing unit, according to the relative attitude of the laser emission unit and the POS unit, the absolute geometric position of the point cloud is acquired based on the relative geometric position of the point cloud, and the space position information of the point cloud is acquired. The vehicle laser radar three dimensional scanning method is advantaged in that the colorful laser spectrum information of a target terrain and the laser point cloud space information are directly and simultaneously acquired, so colorful laser imaging of the target terrain is acquired through three-dimensional reconstruction, and the method can be widely applied to the digital city and smart city fields.