The invention discloses a composite speed regulator with a four-quadrant motor and magnetic gears. The composite speed regulator comprises a first rotor, a second rotor, a third rotor and a stator which are coaxially arranged, wherein the first rotor comprises a first rotor core, a first rotor shaft, a first rotor permanent magnet group and a first rotor fixing disc, the second rotor comprises a second rotor core, a second rotor shaft and a second rotor permanent magnet group, the third rotor comprises a third rotor core, a third rotor magnetic adjustment block group, a third rotor permanent magnet group and a third rotor fixing disc, the stator comprises a stator core, a stator winding, a stator end disc and a stator bearing, and the second rotor core, the third rotor magnetic adjustmentblock group, the first rotor core, the third rotor core and the stator core are sequentially and coaxially arranged along a radial direction from inside to outside. On one hand, the rotational speed of the rotor can be adjusted; and on the other hand, a current can be exported from a stator side and is connected to a power grid when a rotation magnetic field of the second rotor is relatively largein capacity, and the functions of power generation and speed regulation are achieved.