The invention discloses a combined head and a ray imaging device. The combined head comprises a casing, a ray tube, a pump and a tube, wherein the casing is provided with a sealed cavity, the ray tubeis arranged in the sealed cavity, the pump and the tube are arranged in the sealed cavity, the pump is arranged at one side away from the positive pole of the ray tube, one end of the tube is connected with an outlet of the pump while the other end thereof extends to the position near the positive pole of the ray tube, or, the pump is arranged near the positive pole of the ray tube, one end of the tube is connected with an inlet of the pump while the other end thereof extends to the side way from the positive pole of the ray tube. An insulating medium at the position away from the positive pole can be pumped to the position near the positive pole, the insulating medium in the sealed cavity can be driven to form a cycle, and thus, temperature difference between the position of the positivepole and other positions can be reduced greatly, and temperature graded distribution of the insulating medium in the sealed cavity can be more uniform.