Compared with other ship lifts，the Three Gorges ship lift has the characteristic that the upstream water level varies greatly. At the same time，it is also affected by the ship lock filling. Through 13 voyages of 4 ships with different ship types，scales and displacement，the influence of the upstream water level change on the process of ship lift docking at the upstream water level of 145 m of the Three Gorges ship lift is obtained，the main content is fluctuation and variation characteristics of water surface in ship chamber. It provides an important basis for formulating the technical requirements of the three Gorges ship lift.When the upstream water level is between 145 and 150 m，affected by the water filling of the double-line ship lock，the upstream approach channel water level changes significantly aggravate the influence on the upstream docking of ship chamber，and easily leads to insufficient depth of ship chamber，affecting the safety of ship lifts and ships.