The water head and the flow energy of Wan’an 2nd lane lock are all among the highest single-step locks around the world. The filling and emptying system design is the key part of the lock design. According to the design code for filling and emptying system of ship locks and based on analyzing a great number of references，combined with the hydraulic simulation，the filling and emptying system with wall culverts，vertical divider，in-chamber 4 manifolds of Wan’an 2nd lock is put forward and optimized. The results of the model test（scale 1:30） indicate that the layout and design of the filling and emptying system of Wan’an 2nd lane lock is reasonable and doable，thus the filling（emptying） time，vessel’s berthing conditions，and flow conditions around the inlets and outlets and in the approach channels are all satisfying the requirements of the code and design.