The invention provides an automatic shoe sole edge line tracking method based on a robot. The method includes the steps that firstly, a shoe with a shoe sole bound is scanned, after point cloud data are acquired, point cloud feature points are acquired through a weighted PCA three-level-set total least square method, the feature points are divided into blocks and projected to a two-dimensional region, a longest feature line in a two-dimensional image is acquired through a two-dimensional line segment splicing method, the feature line is back projected to three-dimensional space, a closed three-dimensional curve of the edge of the shoe sole is thinned through a space linear projection method, a new curve is generated through a scanned current vamp and the three-dimensional closed curve generated previously in the generation process, the curve is tracked through the industrial robot, and then automatic grinding, liquid medicine coating and glue spraying operation and the like can be achieved. The method can be widely applied to an automatic shoe-making system, and the production efficiency and product quality are improved.