The technology of Reinforced soil has been widely used in civil engineering, its theory has some development . However, there is nearly any study about the theory of Geogrid-reinforced fly ash .In this paper, study the interface characteristics between fly ash and geogrid through the pull-out test,reach the following conclusions:the size of normal stress and water impact the interface parameters between the geogrid and fly ash;the interface friction coefficient between Geogrid and fly ash is small,adding gravel to fly ash can improve the interface friction coefficient between geogrid and fly ash.