The invention relates to a coal angle of repose automatic measurement method by using two radars. The method includes the following steps that: (1) two radars are installed on the big arm of a stacker; (2) the stacker is controlled to move on a slop parallel to a coal pile, when the big arm of the stacker rotates to a position where the two radars can both detect the coal pile, measurement is started, a vertical distance from the radars to the coal pile is required distance information; and (3) during the movement process of the stacker, the change range of the angle of repose of the coal is put into statistics, and the data information of the angle of repose of the coal is analyzed, error data are extracted, and a program outputs the measured change range of the angle of repose of the coal. With the method of the invention adopted, the stacker is automatically and manually operated to rotate or walk, after the distance information is obtained through the two radars, the change range of the angle of repose of the coal can be automatically calculated according to the calculation formula of the angle of repose of the coal, and the information of the angle of repose of the coal can be obtained accurately. The method has the advantages of relatively high measurement efficiency and relatively large measurement area, and can assist in saving costs.