Abstract: The study aims to establish a human gastric cancer orthotopic transplantation model in nude mice and to use 7T MRI for detection. After poorly differentiated human gastric adenocarcinoma SGC-7901 cells were injected subcutaneosly into the right flanks of nude mice, the model of in nude mice was established with orthotopic transplanted cancer of gastric tumor by the Compont^® gel pasted method. 7T MRI scan was conducted on the mice after operating model about 20 days later. Histopathological examinations were carried out on the stomach. Two of three mice on which 7T MRI scan were performed showed visible suspected stomach tumor and their presence was verified again by histopathological examinations; tumor formation rate in the nude mice gastric orthotopic transplantation model was 66. 7%. This study suggested that 7T MRI could be used in the live detection of in situ tumor and that MRI could be used for pre-clinical gastric cancer drug development and clinical gastric carcinoma diagnosis.