The invention discloses a reconstruction method and a reconstruction device for a CT (computerized tomography) image. The reconstruction method for a CT image disclosed by the invention comprises the following steps of: selecting the equal-height projection data on a curve having an approximately curvature with a circular scanning rail; weighting the selected projection data; filtering the weighted projection data along a horizontal direction; and performing a three-dimensional back projection on the filtered projection data along a ray direction. The reconstruction device for a CT image disclosed by the invention comprises a rearrangement unit, a weighting unit, a filtering unit and a back projection unit. The artefact of a cone beam under a large cone angle can be efficiently eliminated by using the technical proposal disclosed by the invention.