Objective:To evaluate the effect of microsurgery for parafalcine meningioma through contralateral longitudinal fissure approach assisted by 3DSlicer software.Methods:From January 2020 to January 2021, 18 patients with parafalcine meningioma in The second hospital of Hebei Medical University were randomly selected as the observation group.The contralateral longitudinal fissure was treated by microsurgery assisted by 3DSlicer software.Before operation, improve the imaging examinations such as brain CT plain and enhancement, magnetic resonance angiography and magnetic resonance venography, establish the models of tumor, superior sagittal sinus and superior cerebral artery by using 3DSlicer software, analyze the positional relationship between tumor and superior sagittal sinus and superior cerebral vein, and remove the tumor by contralateral longitudinal fissure approach.Nineteen patients with parafalx meningioma treated by traditional ipsilateral longitudinal fissure approach from January to December 2019 were selected as the control group.The differences in operation time, intraoperative bleeding, limb muscle strength recovery rate, headache and dizziness relief rate were compared between the two groups.Results:In the observation group, the positional relationship between the reconstructed tumor and the superior cerebral vein above its base was completely consistent with the actual situation during the operation.All patients underwent Simpson grade I resection, and there was no injury to the superior cerebral vein and venous sinus during the operation.The recovery rate of limb muscle strength in the observation group (75%(9/12)) was higher than that in the control group (23%(3/13))( P=0.009). There was no significant difference in the operation time, intraoperative bleeding and the remission rate of headache and dizziness one week after operation in the observation group ( P>0.05). Conclusion:3DSlicer software was helpful for preoperative evaluation of the positional relationship between parafalcine meningioma and the anatomic structures such as superior cerebral vein and superior sagittal sinus.Under the guiding of 3DSlicer software, surgeon removed the tumor totally through the contralateral longitudinal fissure approach, which effectively reduced the operative side injury of the important structures such as superior cerebral vein and functional cerebral cortex, and contributed highly to the recovery of limb muscle strength of patients.