Objective: To explore the possible clinical benefits of CT/MRI image fusion and computer-assisted simulation techniques in guiding type Ⅲ and Ⅳ primary pelvic bone tumor surgeries. Methods: The clinic data of primary bone sarcomas patients treated at Department of Bone and Soft Tissue,Zhenghzhou University Affiliated Cancer Hospital from January 2019 to December 2021 were retrospectively analyzed. Based on whether the CT and MRI image fusion technique was utilized for tumor evaluation and surgical planning,the patients were divided into image fusion group (n=21) or control group (n=27). There were 7 male and 14 female patients included in the image fusion group, with the age of (37.0±10.4) years(range: 18 to 67 years). In the control group, there were 10 males and 17 females with the age of (39.7±15.2) years (range: 16 to 65 years). Both groups included osteosarcoma,chondrosarcoma and undifferentiated polymorphic sarcoma as the pathological diagnosis. Clinical information such as gender,age,pathological diagnosis,location of disease,and metastasis at diagnosis were collected. Surgical related information such as duration of surgery,blood loss,surgical margin,and wound complications were also obtained. Periodical follow-ups every 3 months were performed for all patients to monitor the status of local recurrence,distant metastasis,and survival information. Independent t test and χ² test were used for data comparison between groups. Results: Significant reduced duration of surgery was observed in the image fusion group in comparison with control group both in type Ⅲ and Ⅳ surgeries ((144.0±31.6)min vs. (248.2±56) min,t=-8.084, P<0.01); (173.0±42.0)min vs. (306.1±62.0)min, t=-4.518, P<0.01). Blood loss was significantly reduced in the image fusion group compared with the control group ((484.8±226.3)ml vs. (836.1±359.8)ml,t=-4.130, P<0.01). In addition, significant lower ratio of R1 margin and recurrence rates of type Ⅲ and Ⅳ surgeries were found in the image fusion group comparing with the control group (4.8%(1/21) vs. 22.2%(6/27), χ²=4.214, P=0.040; 4.8%(1/21) vs. 22.2%(6/27), χ²=4.214, P=0.040).In the image fusion group, there were 3 cases of incision infection, 1 of which underwent secondary debridement.And in thecontrol group there were 7 cases of incision infection, 3 of which underwent secondary debridement. There was no significant difference in the incidence of complications between the two groups (14.2%(3/21)vs. 25.9%(7/27), χ²=0.645, P=0.422). Up to the last follow-up, 1 patient died in the image fusion group and 2 patients died in the control group, the difference was not statistically significant (χ²=1.885, P=0.220). Conclusion: Compared with the traditional operation,the image fusion technique can significantly reduce the duration of surgery,blood loss and lower the recurrence rate by achieving better surgical margins.