In order to improve the image quality of multiphase flow process tomography system, a new fusion method of dual mode process tomography based on D-S evidence theory is proposed. For CT system, due to the small angle of projection, the reconstructed image edge prone to distortion, but Ray's hard field characteristics determine the image has a higher resolution; and ECT system, as the “soft field” characteristic of sensitive field, making the edges of the image with the actual situation reconstruction matches, but lower image resolution. Based on the analysis of the imaging mechanism and the aim of the fusion, the D-S evidence theory is applied to the CT/ECT image fusion, and the basic probability assignment is indicated by the distance between the gray value and the cluster center. The simulation results show that the proposed method can improve the quality of reconstructed image, and it is verified by the root mean square error.