Objective To summarize the changc of middle meningeal artery after of encephalo-duro-arteriosynangiosis(EDAS) on Moyamoya disease and argue the probably reason of the changing,Methods Retrospective analysis of the DSA image before and after operations of EDAS on 131 patients with Mdoyamoya disease.Results Operation of EDAS were performed on 249 hemispheres of 131 patients with Moyamoya disease.Connection with vessels on cerebral of middle meningeal artery was found on 54 hemispheres.After the proccdure,new connection was found on 139 hemispheres.We preformed super selection angiograph of superficial temporal artery and internal maxillary artery on 74 hemispheres,and new connection of them were fotund on 58 hemispheres.Conclusions The new connection of the stem and branches of middle meningeal artery with the vessels on brain tissues can be found after procedures of EDAS on patients with Moyamoya disease.The mechanism is not clear.The protection of middle meningeal artery is very important during the procedure.