The invention relates to the technical field of unmanned aerial vehicles, in particular to an automatic track generating method for an unmanned aerial vehicle. The automatic track generating method comprises the following steps: sampling the outer contour of a to-be-calibrated area; carrying out calculation of minimal external convex polygon on a sampling point set, and conversing latitude and longitude coordinates and plane projection coordinates to obtain coordinates and the area of the to-be-calibrated area; obtaining an operation area according to the coordinates and the areas of a field block and an obstacle, and calculating a shortest operation path of the operation area; when the unmanned aerial vehicle operates in the operation area, judging whether the unmanned aerial vehicle safely reaches a next safe take-off and landing point or not at a next waypoint; and if the unmanned aerial vehicle safely reaches the next safe take-off and landing point at the next waypoint, continuously operating, otherwise, returning at the existing waypoint. According to the automatic track generating method, the coordinates and the areas of the filed block, the obstacle and the safe take-off and landing point can be precisely calibrated, and the shortest operation path can be automatically generated, so that the unmanned aerial vehicle can automatically avoid the obstacle while automatically operating according to the shortest operation path, and can automatically select the nearest safe take-off and landing point to carry out automatic return.