The invention discloses a micro-terrain reconstruction method based on laser radar. The method comprises the following steps that (1) mass and discrete laser radar point cloud data are acquired through laser scanning and then point cloud data splicing between different station points is performed, and ground points and non-ground points are separated; (2) point cloud data thinning and boundary point detection of point cloud hole areas or areas of extremely low point cloud density are performed; (3) the fractal feature of a micro-terrain is calculated, and a scale-free area is determined; (4) interpolation is performed in the point cloud hole areas and the areas of extremely low point cloud density by a random midpoint displacement method with normal line control; and (5) micro-terrain reconstruction is performed on the ground points by utilizing a greedy projection triangulation method.