Objective To introduce a imaging classification of middle cerebral artery aneurysms (MCAAs) based on angiography and to explore its guidance value for the clipping surgery.Methods A total of 168 aneurysms were found in 134 patients,of which 143 were MCAAs.According to the direction of aneurysmal projections,they were classified into 4 types:58 point to the temporal side,29 to frontal,52 to the posterior superior part of Sylvius cistern,and 4 to the posterior inferior part of Sylvius cistern. 141 aneurysms were successfully direct clipped.Results According to Glasgow outcome score ( GOS),111 patients (82.8％) had an excellent clinical outcome of GOS 5,14 ( 10.5％ ) GOS 4,4(3.0％ ) GOS 2 ～ 3 and 5 deaths (3.7％,GOS 1 ).Conclusions Preoperative imaging classification of MCAAs may play an important guiding role to the microsurgical treatment which could provide individually optimal strategies for aneurysm dissecting and neck clipping,and could reduce postoperative cerebral vasospasm and improve the therapeutic effect of surgical treatment.