The invention discloses an obstacle detection method and system. The method comprises steps of acquiring point cloud data acquired by N line laser radar; dividing the point cloud data into Q regions including a first region, a second region, ..., and the Q region; carrying out plane fitting on the point cloud data in the first to Q regions to correspondingly obtain first to Q planes; successively acquiring coordinates of obstacles in the point cloud data of the first to Q regions; and carrying out voxelization processing on the coordinate data of the obstacles to obtain coordinate sets of dynamic obstacles and coordinate sets of static obstacles. According to the invention, large-scale compression of three-dimensional point cloud data is achieved; data processing quantity is greatly reduced; the environment is further divided into three parts: a road region (a feasible region), a static obstacle region and a dynamic obstacle region; and better environment information is provided for effective behavior decisions of the robot.