In order to improve the coupling image quality between optical molecular image and computed tomography (CT) image, the free-form surface optical channels of tumor lesion tissue in optical molecular image and CT image are established based on free-form surface optical technology, and dual-mode image fusion display is realized. The design method of microscopic, multi-spatial and multi-focal free-form surface optical lens and imaging surface of tumor lesion tissue is used. The differential equation of fused lens and imaging surface of dual-mode image is established. The light focal change curve of optical surface of the free-form surface in lesion tissue is solved. The optical channel surfaces of lesion tissue free-form surface are discreted and reconstructed by optical reconstruction technique of free-form surface in reverse engineering, which improves the dual-mode image fusion quality of the optical molecular image and CT image. It is reasonable and feasible to use free surface optical channel technology to fuse dual-mode image of the optical molecular image and CT image, which improves the sharpness and signal-to-noise ratio of fusion image signal.