Abstract: The backprojection filtered (BPF) algorithm, which can provide a good reconstruction with data truncation, plays an important role in reconstruction of region of interest for circular cone-beam CT. However, when the cone-angle increases, there will be serious artifacts in the top and the bottom of the reconstruction image. Aiming for solving this problem, the paper rederives the cone-beam BPF algorithm based on fan-beam circle BPF algorithm, then purposes a new weighting function through analyzing the cause of the artifacts. The weighting function based on cone-angle and the axial distance can restrain the artifacts by modifying the solution of the differential backprojection image in the reconstruction process. The experimental results show that the proposed algorithm can inhibit the artifacts and improve the image quality compared with the BPF algorithm at a large cone-angle.