Based on the data of fog, surface observations from 9 weather stations in Langfang, a city in the central seaside plain of North China, as well as the fog data for the eastern central Hebei Province，the historical radiosonde dada from 1980 to 2000, and MICAPS data from 2004 to 2007, the climatic characteristics and relationship between meteorological element distribution and the occurrence frequency of fogs and heavy fogs in Langfang are analyzed. The results show that fog is one of most disastrous weather with high occurrence frequency in Langfang and mainly appears in winter and autumn; favorable meteorological conditions include surface southerly/easterly wind speed being less than 3 m/s, relative humidity greater than 50%, |Δ〖WTBX〗p〖WTBZ〗6| less than 3 hPa, and there excising stable temperature inversion between 1000 hPa and 925 hPa, which can be used as indexes for forecasting the occurrence of fogs and heavy fogs. The forecasting and earlywarning techniques of fog are discussed.