The present invention relates to the field of medical equipment and, particularly, to a structure and method for closed loop control in a CT rotating system. A structure for closed loop control in a CT rotating system comprises a data transmission slip ring, a motor, a servo controller and a transmission belt, with the surface of said data transmission slip ring being provided thereon with a plurality of bar strips, and said closed loop control structure further comprising a signal detector which is used for detecting said bar strips so as to obtain an encoded signal wherein said servo controller is used for determining the rotating speed of the CT rotating system and the position of a bulb tube according to said encoded signal, and for controlling said motor according to said rotating speed and a preset rotating speed. A currently available data transmission slip ring is used as a scale and a signal detector is used to detect this scale so as to obtain an encoded signal, and when compared with the purpose-made encoders in the prior art, its costs are lower, the precision is higher, and the position offset of the bulb tube therein is smaller.
