In order to quantitatively analyse and predict the shiplock operation conditions and give some guidances in the lock scheduling, a traffic simulation model for a double-lane lock was developed based on the discrete event simulation platform of Arena. Taking the double-lane lock of the Changsha hydroproject located at the Xiangjiang River as a case study, the operation state parameters and the maximum throughput capacity of the Changsha lock were simulated and analyzed under different traffic scheduling modes and working conditions, and the reliability of the simulation model was validated by the measured operation data. The simulated results show that the utilization rate of the lock chamber is only improved in each lockage time and that the lock throughput capacity can effectively increase. The greater the number of ships in the lock chambers for each lockage time is, the longer the lockage time and the mean delay are. From the engineering practices it is found that the relatioships between the lock throughput capacity and delays can be coordinated and the navigation lock scheduling can be optimized under the conditions of protection of the lockage safety, according to the traffic demands and the lock working conditions. With the operation state parameters given by the simulation model, which can help to fully grasp a traffic law of the lock system, the lock maximum throughput capacity at different design levels are analyzed or the lock scheduling programs are optimized in dependence on different traffic loads to improve the lock throughput capacity and the quality of service.