A CT device comprising a circular electron beam emission array including a plurality of electron beam emission units that are distributed uniformly along a circle; a circular reflection target disposed to be coaxial with the circular electron beam emission array, wherein the electron beams bombard the circular reflection target to generate X-rays that intersect the axis of the circular electron beam emission array; and a circular detector array disposed to be coaxial with the circular reflection target and configured to include a plurality of detection units which receive the X-rays after they have passed through an object to be detected; wherein the CT device further comprises: a microwave power source configured to generate microwaves of different power levels; a resonance acceleration cavity disposed to be coaxial with the circular electron beam emission array and configured to operate in TM010 mode to receive electron beams emitted from the plurality of electron beam emission units and accelerate the received electron beams; and a coupler disposed between the microwave power source and the resonance acceleration cavity and configured to feed microwaves of different power levels to the resonance acceleration cavity to accelerate the received electron beams so as to generate electron beams of different energies; characterized by a driving mechanism configured to drive the circular electron beam emission array to move to and fro a certain degree when each electron beam emission unit emits electron beams that are substantially parallel to an axis of the circular electron beam emission array in sequence under the control of a control signal, the degree being less than or equal to the angle between two lines, one line connecting one of the electron beam emission units to a center of a circle on which the circular electron beam emission array is positioned, the other line connecting an adjacent electron beam emission unit to the center. a circular electron beam emission array including a plurality of electron beam emission units that are distributed uniformly along a circle; a circular reflection target disposed to be coaxial with the circular electron beam emission array, wherein the electron beams bombard the circular reflection target to generate X-rays that intersect the axis of the circular electron beam emission array; and a circular detector array disposed to be coaxial with the circular reflection target and configured to include a plurality of detection units which receive the X-rays after they have passed through an object to be detected; wherein the CT device further comprises: a microwave power source configured to generate microwaves of different power levels; a resonance acceleration cavity disposed to be coaxial with the circular electron beam emission array and configured to operate in TM010 mode to receive electron beams emitted from the plurality of electron beam emission units and accelerate the received electron beams; and a coupler disposed between the microwave power source and the resonance acceleration cavity and configured to feed microwaves of different power levels to the resonance acceleration cavity to accelerate the received electron beams so as to generate electron beams of different energies; characterized by a driving mechanism configured to drive the circular electron beam emission array to move to and fro a certain degree when each electron beam emission unit emits electron beams that are substantially parallel to an axis of the circular electron beam emission array in sequence under the control of a control signal, the degree being less than or equal to the angle between two lines, one line connecting one of the electron beam emission units to a center of a circle on which the circular electron beam emission array is positioned, the other line connecting an adjacent electron beam emission unit to the center. a microwave power source configured to generate microwaves of different power levels; a resonance acceleration cavity disposed to be coaxial with the circular electron beam emission array and configured to operate in TM010 mode to receive electron beams emitted from the plurality of electron beam emission units and accelerate the received electron beams; and a coupler disposed between the microwave power source and the resonance acceleration cavity and configured to feed microwaves of different power levels to the resonance acceleration cavity to accelerate the received electron beams so as to generate electron beams of different energies; characterized by a driving mechanism configured to drive the circular electron beam emission array to move to and fro a certain degree when each electron beam emission unit emits electron beams that are substantially parallel to an axis of the circular electron beam emission array in sequence under the control of a control signal, the degree being less than or equal to the angle between two lines, one line connecting one of the electron beam emission units to a center of a circle on which the circular electron beam emission array is positioned, the other line connecting an adjacent electron beam emission unit to the center.