ObjectiveTo design magnets to locate colorectal neoplasms based on magnetic tracer technology, and to test its feasibility and safety by animal experiments. MethodsThe magnets used for endoscopic localization of colorectal tumors consist of a tracer magnet and a pursuit magnet, both of which are ring-shaped Nd-Fe-B magnets. Eight healthy Beagle dogs were used as animal models. Tumor locations were assumed in the different parts of the colon and rectum under colonoscopy. The tracer magnet was sent to the hypothetical tumors by endoscopic soft tissue clamp and fixed near the tumors. After 24 hours, laparoscopic surgery was performed under general anesthesia. The pursuit magnet was inserted near the resected colon or rectum through the main operating hole. The tracer magnet was absorbed to the pursuit magnet to identify the location of tumors. ResultsThe tracer magnet and pursuit magnet were successfully designed and processed. The suction force between the tracer magnet and the pursuit magnet at zero distance was 16 N. All the 8 Beagle dogs successfully received indwelling of magnets under colonoscopy, and no magnets fell off after 24 hours. After the placement of pursuit magnet under laparoscopy, the two magnets attracted each other rapidly and accurately, and successfully completed localization of tumor site without any damage during the operation. ConclusionColonoscopy combined with laparoscopy for colorectal neoplasms localization based on magnetic tracer technique is simple, accurate, safe and feasible.