The invention discloses a water level adjustment method for reverse-time consumption on surplus water of a hydropower station, so as to solve the problem of surplus water consumption during an optimized hydropower dispatching process. The method comprises steps: the storage capacity and the generating parameter of the hydropower station with a surplus water time period are acquired, and the initial water storage in the period and the initial storage outflow are solved; the maximum generating flow of the hydropower station is deduced by the initial water storage in the period; the maximum generating flow is compared with the initial storage outflow, the smaller value in the two is used as an updated storage outflow, the initial water storage in the period is then solved in a backstepping mode through a water balance equation, correction and judgment are carried out, and finally, the optimal initial water storage in the period and the corresponding water storage level are acquired. The principle is simple; the operation is easy; and in view of the surplus water period of the hydropower station, through adjusting the initial reservoir water storage in the period as small as possible,the surplus water of the hydropower station in the period reaches the minimum, the method can be applied to actual dispatching and production to solve problems, and the practicability is realized.