Objective: To design pelvic and abdominal external fiducial marker frame for SPECT/CT rigid image registration and to complete image fusion. Methods: Ⅳ-shaped external marker frame was designed. Then the frame, combining the interactive general software that was based on external marker, which was empoldered by ourselves, was used to register and fuse validating the external marker frame and the recurrent lesions SPECT/CT transaction of patients with colorectal cancer. Result: The Ⅳ-shaped external marker frame could be easily fixed to the body, and the relative position of external marker point maintains in the same station during the different scanning procedure by SPECT/CT. With combination of marker frame and the image fusion software based on that, the recurrent lesions of colorectal cancer SPECT/CT image fusion was accomplished on a low cost PC. Conclusion: The Ⅳ-shaped external marker frame suited to the image fusion software of pelvic and abdominal SPECT/CT we designed could be easily fixed to the body, which was qualified to multi-modal transaction image fusion.