Abstract: A method for detecting a surface gradient of an unstructured road based on Lidar includes: obtaining an environmental point cloud of a target region by using a Lidar, and filtering out a point cloud of a non-surface region to obtain a point cloud of a surface region; calculating a normal vector of the point cloud of the surface region, and obtaining an included angle of the surface of each region relative to a coordinate system of the Lidar; and obtaining pitching angle information of a vehicle at this time from a vehicle-mounted inertial measurement unit (IMU), and correcting the included angle with the pitching angle information to obtain the gradient of the surface of each region.