Cycloid planetary transmission gear based on line-surface conjugation

The invention discloses a cycloid planetary transmission gear based on line-surface conjugation, and relates to a cycloid planetary transmission gear which comprises a cycloid pin wheel planetary transmission meshed pair. A smooth curve line inverted L (2) is selected on a gear surface of a gear in the meshed pair, the main normal vector direction is consistent with the normal direction of the gear surface, and the curve line inverted L (2) and the gear surface of another gear in the meshed pair form line-surface conjugation mesh; the gear surface of the gear is a tubular meshed surface which is a sphere family enveloping surface sigma (3) of which the sphere center moves along an equidistant line inverted L (3); the equidistant line inverted L (3) is a smooth curve line which has a distance of r from the main normal vector direction; the spherical radius of spheres in the sphere family is the distance r between the equidistant line inverted L (3) and the smooth curve inverted L (2), and the r is less than th