To the problem of excessive water level variation in the upstream approach channel during the irrigation time of the Three Gorges ship lock when the upstream water level of the Three Gorges ship lift is below 150 m,this paper studies the relationship between the water level of the upper lock of the Three Gorges ship lift and the irrigation time of the Three Gorges ship lock.Theoretical analysis and numerical calculation methods are used to study the variation law of the water level at the upper lock of the Three Gorges ship lift after the wave superposition in the irrigation approach channel of the north and south lines of the Three Gorges ship lock.The mathematical relationship between the maximum water level change at the upper lock head of the Three Gorges ship lift and the double-line irrigation time of the Three Gorges ship lock is obtained,and the early warning method for the upstream water level of the ship lift is proposed.By comparing the actual data with the theoretical prediction and calculating the error value,the accuracy results of the prediction model are obtained.The results show that the early warning method of upstream water level of the ship lift established by the prediction model can provide reference for the safe operation of the ship lift.