Abstract: Using the data of buoy station in Beibu Gulf in 2016-2017， the feature of sea fog over Beibu Gulf was analyzed． It showed that the sea fog appeared for 37 days in 2016 and 19 days in 2017. The maximum occurrence days of yearly sea fog was in March, the next was April, and the minimum was in December and in the period from June to October. The peak of sea fog formation time was between 03:00 and 05:00, and the peak of dissipation time was between 08:00 and 10:00. The duration of sea fog lasted for no more than 3 hours. Comparisons of atmo spheric visibility and relative humidity among the buoy station, Beihai and Weizhou Island stations showed that the mean atmospheric visibility and relative humidity of Weizhou Island station were closer to the buoy station during sea fog. The mean atmospheric visibility at Weizhou Island station was 0.7-3.3 km larger and the mean relative humidity was 1.6%-2.4% smaller than those at the buoy station. Different sea fog processes have different influence systems and the duration and atmospheric visibility of sea fog and land fog could be very different. When the fog was caused by warm low or high pressure in the southwest, the atmospheric visibility at Weizhou Island station was closer to that at the buoy station but it was quite different from that at Beihai station. When the sea fog was caused by the uniform pressure field, the atmospheric visibility changed consistently at these three stations where the fog appeared in the morning and dissipated in the afternoon.