With the vigorous development of cruise market in Asia, the passenger flow systems at each port in different countries must face the issue of the growing number of passengers. Therefore, it is a critical issue to know how to examine the efficiency of the systems and to allocate limited resources, thereby improving the strategy. This research takes Keelung Port as a case study. Based on applying Discrete Event Simulation(DES), this paper constructs a simulation model of cruise passenger flow system at Keelung Port, in order to identify the current bottleneck of the system and its cause. This paper not only realizes the influence of the modifying element by single-criteria sensitivity analysis, but also comprehends the interplay of different elements by multi-criteria sensitivity analysis. Subsequently, it will achieve the equilibrium between cost and efficiency to propose the optimal improvement plan.