Objective To investigate the operative techniques of microsurgery treatment of M1 segment of middle cerebral artery (MCA) aneurysms via pterional approach in 132 cases.Methods Retrospectively analyzed the clinical manifestation,angiograms,and surgical operation data of 132 patients with M1 segment of MCA aneurysms who underwent microsurgery through pterional approach.Results Preoperative digital subtraction angiography (DSA) was conducted in 121 cases to identify the size,shape,orientation and relationship with blood vessels around the MCA aneurysms.The other 11 cases underwent emergency operation.Among the 132 cases,72 patients were discharged in good condition according to Glasgow Outcome Scale; 41 patients were in poor condition; 19 cases were dead or in predying state.Postoperative CT showed that49 cases occurred new infarction and 7 cases developed hydrocephalus or enlargement of ventricles.Ventriculoperitoneal shunt was conducted in 2 cases.Intraoperation rupture and bleeding of aneurysms occurred in 17 cases.Conclusion The aneurysms in M1 segment of the middle cerebral artery are mostly located in the bifurcation of M1 segment.Most branches and perforating arteries stem from middle cerebral artery trunk.Patients with Hunt-hess grade Ⅰ-Ⅲ MCA aneurysms or with Hunt-hess grade Ⅳ,Ⅴ should be treated with microsurgery as soon as possible.Inside Sylvian fissure approach is the most frequently adopted in microsurgery via pterional approach.It is key for the success of the operation to preoperatively understand the anatomy surrounding the aneurysms,have good microsurgical skills and employ correct methods of preventing and managing of rupture of aneurysm.It can relieve the secondary cerebral vasospasm to clear up hematocele in the cisterns or to wash the cisterns or use adhesive wound dressing on blood vessels during operation using papaverine.