1. A space segmentation method for 3D point clouds, comprising: equally segmenting a space of the 3D point clouds into a plurality of grid cells; establishing a base plane corresponding to a bottom part of the space of the 3D point clouds; accumulating points of all grid cells located perpendicular to the base plane in a grid cell of the base plane; and segmenting, the grid cell in which the points are accumulated, into an object part and a ground part according to the number of accumulated points.