If the Baima junction lock for resuming navigation project in Xiujiang River is designed as the conventional single-step lock,the flow supplied by the river will be less than the water consumption of a navigation lock during the dry season,and cannot meet the water demand for lockage.Based on the research achievements and experiences at home and abroad,we propose a layout scheme of filling and emptying system with two open water saving basins,calculate and analyze the corresponding hydraulic characteristics with various valve opening and closing schemes by one-dimensional mathematical model,and obtain reasonable valve opening and closing schemes,water saving rate and hydraulic characteristics of lock chamber.The results show that,in the case of an optimized valve scheme,the filling and emptying time is controlled within the range of 12 minutes,and the water saving rate is at least 49%.The proposed schemes of water saving lock can deal with the lack of water during the dry season.