When we determine the lock capacity,the transportation demand and the vessel development need to be taken into consideration to avoid ship lock becoming a bottleneck of the development of waterway transportation.After analyzing and predicting the increase of the throughput of Tai’erzhuang lock,the current status and the tendency of vessel dimensions,three main indicators of a lock of the design target year are acquired by computer simulation method,which are the average total tonnages of passing vessels per lockage,average number of passing vessels per lockage and occupancy rate of chamber.Those indicators can be used for calculating the capacities of the planned Tai’erzhuang third-lane lock under different chamber dimensions,and checking the capacity of the running lock at Tai’erzhuang.In the end,the reasonable or suitable chamber dimensions from different options are chosen according to the simulation results and considering conditions such as predicted throughput of lock,vessel development and water-saving when lock operating.