Abstract: Objective: To determine a reasonable surgical margin for resection of osteo-sarcoma using X-ray, MRI, bone scan (ECT), visual examination and pathological methods and to study the influencing factors for limb salvage sur-gery. Methods:From May 2007 to July 2008, 36osteo-sarcoma patients underwent preoperative X ray, MRI, bone scan (ECT) and pathologic examinations in our hospital. Extent of surgery was defined based on the outcome of imaging exami -nation. The excised tumors were split open, utilizing the electric saw or osteotome, along the coronal and sagittal planes of the tumor bone, and the sample was divided equally into two halves, taking one half as the object for study. Macroscopic measurements of the tumor size were taken before subdivision of the tumor samples. All materials with coronal cross-sec-tions along the anatomic landmark were cut into 10-mm sections and then the complete layer was dissected into 1 × 1cm sections for routine examination. Digital photography was used for recording the results of the X-ray, MRI and ECT exami-nations in the sample collection, and data transmission into the computer. Adobe Photoshop 7.0 software was used to mea -sure the length of the tumor. The analytic software SPSS 11.5 was used for data processing and t test (a= 0.05) was used for data analysis. Results:A total of 19patients met the criteria of inclusion. There was an obscure boundary of the soft tis sues shown in the X-ray examination, however, in the MRI scan, clear margin of the tissues could be seen, with an edema zone, hemorrhage and hyperemia, and the infiltrating growth of most tumors along the intercellular space of the adipocytes. There were significant differences between the pathologic and the X-ray or ECT examinations, and there were no signifi-cant differences among pathology, MRI scan and visual inspection. Conclusion:The relative error is minor in the MRI measurement. Preoperative MRI weighting and fat-suppression sequence images show the full range at 1.5 cm beyond the tu -mor margin is the safest plane to resect the bone and salvage the limb. The factors affecting limb salvage in the treatment of osteo-sarcoma are varied and need comprehensive consideration.