Objective To explore the difference of invovling rate in intracranial arteries and hemodynamics in extracranial arteries between child group and adult group moyamoya disease.Methods In order to differentiate the child and adult group moyamoya disease,the hemodynamic parameters such as pulse index(PI), resistance index(RI), mean velocity(Vm),systolic velocity/distolic velocity(S/D) were studied by ultrasound and the involving rate of intercranial arteries were studied by digital subtraction angiography.Results ① The involving rate of posterior cerebral artery(PCA) in child group was signifiicantly higher than that in adult group,but no difference in middle cerbral artery(MCA) and anterior cerebral artery(ACA); ② The mean flow velocity of vertebra artery(VA) were significantly reduced but RI,PI,S/D increased in child group than that in adult group moyamoya disease.No difference existed in other extracranial arteries.Conclusions The difference of extracranial arteries hemodynamics owes to the difference of intracranial artery involving rate.