A computed tomography (CT) machine system and a state monitoring method are described. The CT machine system comprises a drum-shaped component, a 3D camera, and a control system. The drum-shaped component comprises a cylindrical body, with the center of the cylindrical body being provided with a hollow portion which is rotationally symmetrical about the central axis of the cylindrical body, a rotating component disposed in the cylindrical body rotating about the central axis, a plurality of trigger marks arranged in the rotating component, and a window provided in the cylindrical body. The 3D camera generates image data that is transferred to the control system, from which the control system determines state data of the CT machine. The 3D camera captures an image of the trigger marks through the window to generate marked image data.