Objective To investigate the effectiveness of Multimodal image fusion and 3D reconstruction techniques in the surgical treatment of posterior cranial fossa tumours surgery.Methods Retrospective analysis of medical records of 19 patients with posterior cranial fossa tumours who underwent surgical treatment between January 2022 and September 2023 in Department of Neurosurgery,the Affiliated People's Hospital of Jiangsu University.All patients underwent preoperative CT and MR imaging of the head,and these image data were input into an image fusion workstation for image fusion and 3D reconstruction.The surgeon then used these fused images for spatial assessment of the tumour and simulation of surgical access.Results The multimodal image fusion techniques could clearly show the anatomical relationship between the tumour of the posterior cranial fossa and the surrounding structures,and there were 15 cases of total resection of the tumour in 19 patients(78.9％),4 cases of subtotal resection,and no perioperative death patients.Postoperative complications included cerebral oedema in 2 cases,intracranial infection in 1 case,facial paralysis in 2 cases,and dysphagia in 1 case.According to the feedback from the surgeons,the multimodal image fusion techniques showed significant value in surgery in 16 cases and ancillary value in 3 cases.Conclusion Multimodal image fusion technology and 3D reconstruction techniques in can accurately and clearly show the spatial relationship between the tumour in the posterior cranial fossa and the surrounding important tissues,which helps the surgeon to more accurately design the surgical incision and choose a more reasonable surgical approach.It has a high auxiliary value for the successful completion of surgery.