The uneven flow of side orifice outlet of the long-culvert filling and emptying system inside the lock wall is the main reason for the overall flow and the wave motion in the lock chamber.In order to study the hydraulic characteristics of the side branch orifice in the uniform arrangement,we analyze the influence of water delivery mode,water head and valve opening time on the outflow of the side branch orifice by CFD numerical simulation.The results show that with the increase of filling and emptying time,the flow rate of each branch orifice increases first and then decreases,and the relative difference of flow distribution between branch orifices also presents a similar trend.When the lock chamber is filling,the flow distribution between branch orifices gradually increases from upstream to downstream and then decreases slightly at the end,and the branch orifice with maximum flow rate is roughly located in the latter 13 of the outlet section.When the lock chamber is emptying,the flow distribution between branch orifices increases gradually from upstream to downstream.The filling and emptying time of lock chamber is proportional to the water head and the valve opening time,and the filling time is slightly shorter than the emptying time when all others are same.