This paper discusses the fluctuating character of the water in Chamber 1 when No.2 chamber head is operating as the first one under the four-steps shiplock operating mode, expatiates the forming principle of the fluctuation, analyzes the impact on the water fluctuation in Chamber 1 when No.2 chamber head is operating as the first chamber head, puts forward the valve opening pattern satisfying the safety demand when Chamber 1 is waiting, and tests the berthing condition of the ships in Chamber 1 by the experiment with real ships. The facts show that during the course of the Three-Gorges shiplock being fulfilled under the four-steps shiplock operating mode, the ways transferring the ships downriver from near frusta to chamber 1 can increase passing ability of about three ships per day, producing huge navigation benefit.