Based on the observation data of island stations, buoy stations, and coastal stations in Shanghai during 2016-2020, sea fog events at six stations were identified and classified. On this basis, the spatio-temporal characteristics of sea fog events and the changes in space, season, duration, intensity, and generation and disappearance time of different types of sea fog were analyzed. The results showed that there were generally 20-30 sea fog events in different regions throughout the year, but there were significant differences in time and space. Radiation fog is the most common type of sea fog, followed by precipitation fog, and advection fog occurs more frequently at Yangshan station and Haijiao buoy. The seasonal variations of different types of fog varies greatly in different sea areas. In the Yangtze River Estuary sea area，radiation fog and precipitation fog occur every month, but radiation fog is the main type，advection fog mainly occurs in winter and spring, but its frequency is relatively small; The Jinshan and Yangshan sea areas are dominated by radiation fog every month, with precipitation fog and advection fog mainly occurring in spring, summer, and winter. The duration of advection fog is generally longer, while the duration of precipitation fog and radiation fog is shorter. The lowest atmospheric visibility value in precipitation fog events is generally higher than that in radiation fog and advection fog, and advection fog produces the most severe fog events. Precipitation fog can occur at all times of the day, while radiation fog and advection fog mainly occur at night. The dissipation time of radiation fog and advection fog is mainly 1-5 hours after sunrise, and the dissipation time of precipitation fog is more dispersed.