The invention relates to an embedded planetary speed reducing mechanism. A sealing groove, a sliding groove and a planetary groove are formed in a shell; a primary planetary
gear train and a secondary planetary
gear train are arranged in the shell; the primary planetary
gear train comprises planetary gears II, a planetary carrier II, an inner gear ring and an input gear ring, the input gear ring is a sun gear of the primary planetary gear
train, and the planetary carrier II comprises a planetary gear ring and a planetary output shaft; the
planet output shaft is connected with three cantilevers on the inner wall of the
planet gear ring through three cantilevers and shafts, and the
planet gears II are arranged on the planet carrier II in a rotatable
annular array mode through the shafts; the input gear ring is the input end of the primary planetary gear
train, and the input gear ring is the output end of the secondary planetary gear
train; and the output module comprises a planet output shaft, a gear ring output shaft
barrel and a terminal output shaft, a selection clamping module comprises a sliding groove and a limiting frame, the
insertion end of the limiting frame is limited in the sliding groove in a sliding mode, a
brake block of the limiting frame is made to clamp the inner gear ring or the planet gear ring, and output is conducted outwards through the planet output shaft or the gear ring output shaft
barrel.