Combined with the two methods of water level backward moving method and Manning formula,this paper takes Lijiadu station in Fuhe River as an example to discuss how to extend the water level discharge relationship in the flood fluctuation measuring station,and draws the following conclusions:1)through the trial calculation of water level backward moving method in this station,the backward moving period of 1.5h can realize the single value of Lijiadu high water rope jacket curve;2)Manning formula can extend the single valued curve and through the back calculation of water level backward moving,the extension of water level discharge relationship affected by flood fluctuation can be realized;3)the combination of the two methods can provide reference for patrol survey analysis and test results inspection of survey stations affected by flood fluctuation.