String-type planetary reducer for electric submersible thickened oil screw pump

The invention discloses a string-type planetary reducer for an electric submersible thickened oil screw pump. The string-type planetary reducer for the electric submersible thickened oil screw pump comprises a box body. A sun gear axle and more than two sets of planetary gear transmission assemblies respectively arranged along the axial direction of the sun gear axle are arranged in the box body; each planetary gear transmission assembly comprises a sun gear, an inner gear ring, a planetary gear and a planetary gear carrier, wherein the sun gear is fixedly arranged on the sun gear axle; the inner gear ring is fixedly arranged on the box body; the planetary gear is arranged between the sun gear and the inner gear ring; and the planetary gear carrier is used for supporting the planetary gear. The planetary gear carriers in adjacent two sets of planetary gear transmission assemblies are connected through a planetary gear carrier connecting piece; the top end of the planetary gear carrier located at the uppermost end is provided with a reducer output shaft. According to the string-type planetary reducer for the electric submersible thickened oil screw pump, torsional power can be jointly transmitted by a plurality of planetary gear trains, so that the torsional power is evenly loaded, and the service life is prolonged.