Satellite photographs and weather charts during the 1983 to 1994 marine fog seasons were used to analyze the distribution and formation, movement pattern and occurrence frequency of marine fog. The results showed that during the marine fog seasons, the SST in the Yellow and East China Seas was optimum for marine fog formation as soon as S-SE winds occur. Three patterns for favering marine fog formation and the synoptic type for following day predicting marine fog were indicated. Finally, a heavy fog case is discussed in detail.