Abstract: Objective To compare the difference of the CT,MRI and CT-MRI fusion imaging,investigate the advantages of CT-MRI fusion imaging for delineation of target areas in head and neck tumor.Methods The two images for per patient in 35 patients with head and neck cancer were received through CT,MRI scans and image fusion software,and the same physician on the same patient at the same time period delineated the target areas based on CT,MRI and image fusion to compare their tumor target volume(Gross Tumor Volume,GTV)of the primary lesion.Results GTV_CT,GTV_MRI,GTV_CT-MRI average were 21.22 ± 1.56,23.64 ± 1.30,29.08 ± 2.09cm³,GTV_CT compared with GTV_MRI(t=7.05,P＜0.01),GTV_CT-MRI compared with GTV_CT(t=-17.82,P＜0.01); GTV_CT-MRI compared with GTV_MRI(t=13.08,P＜0.01).Conclusion The delineation of CT-MRI fusion for the tumor target areas was broader than the MRI or CT images alone in the head and neck cancer,CT-MRI fusion imaging technology can improve the accuracy of the target outline and more conducive to guide the implementation of precise radiotherapy.