The invention discloses a bucket wheel unloading device of an arm bucket wheel machine. The device comprises a bucket wheel, a bucket wheel chute and a crushing device; the bucket wheel chute is mounted on the inner side of the bucket wheel; the crushing device is mounted in a discharge port at the lower end of the bucket wheel chute above a reception conveying belt of the arm bucket wheel machine; the crushing device comprises a crushing roller set I and a crushing roller set II; each crushing roller set comprises a chain, a gear, a motor, a rotating shaft, a crushing blade and a bearing; two rotating shafts form one set, and are assembled in parallel; each rotating shaft is assembled with multiple crushing blades to form a crushing roller; two motors respectively drive the crushing roller set I and the crushing roller set II to rotate; and two crushing rollers of the crushing roller set I and two crushing rollers of the crushing roller set II are across assembled to realize the work of cutting and crushing agglomerated chemical fertilizers through rotation of the crushing blades in different directions.