A method and apparatus for correcting a focus of a CT device are provided. The method includes: calculating a total focus shift according to scanning data and correcting, when the CT device is running, a deflection of an electron beam emitted from a ray source of the CT device, based on the total focus shift. The device includes: a shift calculation module, configured to calculate a total focus shift according to scanning data and a shift correction module, configured to correct, when the CT device is running, a deflection of an electron beam emitted from a ray source of the CT device, based on the total focus shift.
