Abstract: Streambed structures are developed in many mountain incised rivers as a result of fluvial morphology.They affect the further morphological process in some aspects such as channel stability enhancement.In order to study the role of the structures in morphological evolution in incised river channels,the landform features and structures were investigated and analyzed in the typical incised rivers.The results show that landslides and avalanches would likely occur due to earthquakes or rainstorms when the valleys are deeply incised and the valley slopes exceed a critical value.Thus,the river evolution will enter to a new phase of fluvial geomorphology after incision widening.A large amount of substances enters into channels enhance the intensity of streambed structures,and sustain higher gradients and form river knickpoints.This reflects the river system's selfadjustment,and in turn,reveals the existence of a negative feedback mechanism that is "incisionlandslides structures developmentincision impededequilibrium".The mechanism can lead the incised river system into the state of equilibrium,in case of invariable input conditions.