A cup holder assembly, comprising: a mounting barrel having a circumferential wall extending in a vertical direction and a top opening obliquely extending downwards from a front portion of the mounting barrel to a rear portion of the mounting barrel, the circumferential wall enclosing an accommodating cavity extending in the vertical direction; a synchronizer disc arranged in the accommodating cavity; a cup holder rotatably fixed to the synchronizer disc and having an axis of rotation extending in a width direction of the cup holder; a lifting mechanism connected to the synchronizer disc; and an angle adjusting mechanism configured to be connected to each of the cup holder, the synchronizer disc, and the lifting mechanism, so that the cup holder is rotatable about the axis of rotation while rising and lowering in the vertical direction, so as to move between an inclined initial position in which the cup holder is located at the top opening and a horizontal operating position in which the cup holder is located in the accommodating cavity, wherein the angle adjusting mechanism comprises: a planetary gear; a sun gear which is rotatably fixed to the bottom wall and which comprises a second circumferential tooth portion meshing with the first circumferential tooth portion and an annular wall extending along a central axis of the second circumferential tooth portion; and a connector which is fixed to the annular wall in a liftable manner and which is provided with a first rotating shaft pivotally connected to the cup holder, characterized in that the planetary gear is rotatably fixed to a bottom wall of the synchronizer disc and comprises a conical tooth portion fitting with the lifting mechanism and a first circumferential tooth portion extending along a circumferential edge of the conical tooth portion. a mounting barrel having a circumferential wall extending in a vertical direction and a top opening obliquely extending downwards from a front portion of the mounting barrel to a rear portion of the mounting barrel, the circumferential wall enclosing an accommodating cavity extending in the vertical direction; a synchronizer disc arranged in the accommodating cavity; a cup holder rotatably fixed to the synchronizer disc and having an axis of rotation extending in a width direction of the cup holder; a lifting mechanism connected to the synchronizer disc; and an angle adjusting mechanism configured to be connected to each of the cup holder, the synchronizer disc, and the lifting mechanism, so that the cup holder is rotatable about the axis of rotation while rising and lowering in the vertical direction, so as to move between an inclined initial position in which the cup holder is located at the top opening and a horizontal operating position in which the cup holder is located in the accommodating cavity, wherein the angle adjusting mechanism comprises: a planetary gear; a sun gear which is rotatably fixed to the bottom wall and which comprises a second circumferential tooth portion meshing with the first circumferential tooth portion and an annular wall extending along a central axis of the second circumferential tooth portion; and a connector which is fixed to the annular wall in a liftable manner and which is provided with a first rotating shaft pivotally connected to the cup holder, characterized in that the planetary gear is rotatably fixed to a bottom wall of the synchronizer disc and comprises a conical tooth portion fitting with the lifting mechanism and a first circumferential tooth portion extending along a circumferential edge of the conical tooth portion. a planetary gear; a sun gear which is rotatably fixed to the bottom wall and which comprises a second circumferential tooth portion meshing with the first circumferential tooth portion and an annular wall extending along a central axis of the second circumferential tooth portion; and a connector which is fixed to the annular wall in a liftable manner and which is provided with a first rotating shaft pivotally connected to the cup holder, characterized in that the planetary gear is rotatably fixed to a bottom wall of the synchronizer disc and comprises a conical tooth portion fitting with the lifting mechanism and a first circumferential tooth portion extending along a circumferential edge of the conical tooth portion.