The sediment transport under unsteady flow in open channel is the basis of river sediment movement mechanics.Comparing the sediment data under unsteady flow both at home and abroad,we find that the researchers have not reached a consistent conclusion,which indicate that the unsteady flow and sediment is still in the starting stage.By defining a new unsteady factor,we integrate all the researchers’ data and find the universal rule concerning sediment transport of unsteady flow.