An automatic degradable sphere dropping device for an unmanned aerial vehicle, relating to the technical field of plant protection mechanism. Said dropping device comprises a ranking portion, an adjustment portion and a dropping portion. The ranking portion consists of a rotating shaft (2), blades (1a, 1b), a rolling bearing (12), a sphere cabinet (3), a coupling (9b), a motor support (11b) and a motor (10b). The adjustment portion consists of a housing (501), a bevel gear transmission group (502, 503) and adjustment sheets (504a, 504b, 504c). The dropping portion consists of circular wheels (8a, 8b), a spur gear group (6a, 6b), a guide rod (13), a coupling (9a), a motor support (11a) and a motor (10a). Said dropping device may rank the degradable spheres vertically in sequence, being adaptable to spheres of different volumes, being highly universal, and being capable of dropping the spheres at intervals, with high precision and automation degree.
