[Objective]To compare the clinical application value of fusion imaging of ultrasound(US)and computed tomogra-phy(CT)or magnetic resonance(MR)(US-CT/MR fusion imaging)and fusion imaging of US and three-dimensional US(US-US fusion imaging)in treatment response assessment of thermal ablation combined with other surgeries and procedures.[Methods]This clinical research included patients confirmed with liver cancers that underwent thermal ablation combined with other surgeries and procedures from Aug to Dec 2015. Both US-CT/MR and US-US fusion imaging together with contrast-enhanced US was applied on the same patient to assess the treatment response of the thermal ablation during the ablation procedure. The applicable rate ,the success rate of registration and the duration required for fusion imaging were recorded and compared. Contrast-enhanced CT/MR 1-3 months after the ablation procedure was taken as the golden reference of the technical efficacy rate for ablation.[Results]67 liver can-cers in 50 patients were enrolled in this clinical research in total. The ablation of 47 lesions in 37 patients were combined with artifi-cial hydrothorax or ascites ,14 lesions in 10 patients with open surgeries and 8 lesions in 5 patients with laparoscopy surgeries. The applicable rate for US-US fusion imaging[52.5%(35/67)]was lower than that for US-CT/MR fusion imaging[98.7%(66/67)](P<0.001)while the success rate of registration for US-US fusion imaging[88.6%(31/35)]was higher than that for US-CT/MR[66.7%(44/66)](P=0.018). The duration time for US-US fusion imaging[3.8 min(2.7~10.0 min)]was significantly shorter than that for US-CT/MR fusion imaging[5.5 min(3.0 ~ 14.0 min)](P < 0.001). No major complication related to ablation was observed. The technical efficacy rate for ablation was 100%(62/62)according to the contrast-enhanced CT/MR 1-3 months after the ablation proce-dure.[Conclusion]For ablation combined with other surgeries and procedures ,US-US fusion imaging should be priority when the tumor is conspicuous in US,especially for cases combined with open surgeries while US-CT/MR fusion imaging should be selected in some cases when the tumor is inconspicuous on US.