Using dual energy CT method to detect multilayer spherical shell components with great density difference, it is necessary to study the image reconstruction method based on two sets of projection data. The Method of Reconstructed at First and then Fused Based on Images cannot make full use of dual energy X-ray projection information, by which simulation research shows it is difficult to get good reconstructed image. On this basis, the paper focuses on the Method of Fused Based on Projection Data at First and then Reconstructed. Firstly, considering the structure characteristics of the multilayer spherical shell components with great density difference, the X-ray projection sinogram with clear regional distribution can be obtained through a specially designed scanning mode. Then extract effective projection data respectively from the high and low energy X-ray projection sinogram, do the consistency processing, and integrate them to become one sinogram. Finally use the FBP algorithm to complete the image reconstruction process. The concrete realization of the algorithm based on projection data fuse for dual energy CT of multilayer spherical shell is summarized, and computer simulation shows that better reconstructed images can be obtained.