Objective To investigate the effect and mechanism of subarachnoid drainage on delayed cerebral vasospasm(DCVS) after subarachnoid hemorrhage in rabbit model.Methods Rabbit subarachnoid hemorrhage(SAH) model was induced by injecting autogeneic blood into the cisterna magna twice.The animals were divided into SAH group,saline group and treatment group.The rabbits were killed and basilar arteries were taken out on days 1,3,5,7,and 10 after SAH.Perimeter of basilar artery was measured with Leica-Q550CW image analysis system.The data was analyzed with statistics software SPSS13.0.Results On day 3 after SAH,perimeters of basilar arteries in SAH group and treatment group were shorter than that in saline group.On day 5 after SAH,perimeter of basilar artery in treatment group was longer than that in SAH group,and had no statistically significant difference with saline group.On day 7 after SAH,the perimeter of basilar artery in treatment group was longer than those in SAH group and saline group.Conclusion Subarachnoid drainage is effective on delayed cerebral vasospasm after subarachnoid hemorrhage.