1. An apparatus for beam hardening artifact correction of CT image, comprising: a bone tissue image obtain module to extract a bone tissue image from a reconstructed original image; a first correction module to increase a current CT value of the bone tissue image; an orthographic projection module to perform an orthographic projection on the bone tissue image with the CT value being increased to obtain an orthographic projection data of the bone tissue image; and a correction image obtaining module to perform image reconstruction according to the orthographic projection data of the bone tissue image described above and obtain a corrected image.