The invention provides an MDOF (Multiple Degree Of Freedom) exposure control device for a medical X-ray machine with a C-shaped arm, which belongs to the technical field of medical instruments. The exposure control device comprises a control circuit, a matched X-ray tube component, and a matched MDOF motion control system. The circuit of the exposure control device comprises a control module formed by a singlechip, an interface circuit of the X-ray tube component, and an interface circuit of the MDOF motion control system. The exposure control device is characterized in that certain X rays can be emitted by the X-ray tube component via certain time sequence and voltage converted by the control circuit; and the C-shaped arm is controlled by a serial port in an MDOF manner. The exposure control device has the advantages that the matched X-ray tube component, the matched MDOF motion control system and the matched control circuit are adopted, so that the seamless connection between the control circuit and the X-ray tube component as well as the seamless connection between the control circuit and the MDOF motion control system is realized, and the cost is also reduced.