The use of shore power is an important means to reduce pollutant emissions from ships approaching the port. In order to quantify the effect of shore power emission reduction, based on the data statistics of different terminals, this study proposes a three-level calculation method of pollutant emission reduction based on shore power consumption, shore power use time/throughput of ships using shore power, and the number of ships using shore power, so as to quantify the effect of ships using shore power and promote the use of port power.