The invention discloses a planetary gear box capable of realizing bidirectional self-locking. The planetary gear box comprises a gear box driving device, wherein an insertion groove element and a gearshaping slide block are arranged at the output end of the gear box driving device, the gear shaping slide block is controlled to rotate forwards or backwards by the gear box driving device and is separated from the limitation of the insertion groove element, and the gear shaping slide block is connected with an output shaft through a connecting shaft; when the gear shaping slide block is controlled to rotate by the gear box driving device, the output shaft outputs power; and when the gear box driving device stops driving the gear shaping slide block, the output shaft rotates reversely at anyangle, the gear shaping slide block can slide and is connected with the insertion groove element in an inserting mode, and the insertion groove element restricts the gear shaping slide block from rotating to realize self-locking. The self-locking function is realized by inserting the gear shaping slide block into the insertion groove element. The external reverse input load does not act on a gearand does not pose a threat to the safety of the gear. At the same time, the safety of the gear is further protected, and the reliability of the whole gear box is improved.