Abstract: Ship exhaust emissions are an important source of global environmental pollution, and emission monitoring is one of the primary approaches to obtain ship emission data. The proper selection of monitoring methods can effectively improve the accuracy of ship emission inventories. This paper comprehensively reviews the differences, scope of application and adaptability of the precision system of various ship monitoring methods, and evaluates the ability of different methods in quantifying the pollutant emission factor (EF). The results show that there are significant differences between the different monitoring methods. The use of plume monitoring is able to capture long-term emission trends and regional dispersion patterns, while the use of stack gas monitoring is more sensitive to transient emission anomalies. Stack gas monitoring is suitable for high-precision source emission research, whereas plume monitoring is more appropriate for assessing the regional environmental impacts of ship emissions. Comparison of the EFs showed that the data obtained from both the ISO-compliant monitoring platform (ICMP) and the custom-developed portable shipborne monitoring platform (CPMP) provided reliable monitoring results, but there were significant differences in the accuracy of the monitoring data for different air pollutants. The ICMP is suitable for standardized rapid screening of ship emissions, compliance supervision, and EFs studies of large ocean-going vessels. The CPMP can be applied to pollution contribution evaluation and emission inventory optimization, and is particularly suitable for vessels where on-board testing is difficult to implement, enabling research on emission characteristics under actual navigation conditions.