A method and a robot of mapping. The method of mapping includes: acquiring a two-dimensional point cloud image of a motion space, wherein the two-dimensional point cloud image is a data set composed of several point cloud data; determining a wall in the motion space according to the two-dimensional point cloud image; determining a main traveling direction according to the wall. The method adds up a function for searching the main traveling direction, and can provide the robot with optimal main traveling direction, which makes the map composition smoother, more regular and intuitive, and conforms to people's using habits, thereby facilitating improving the user experience.