Using the air pollution and meteorological data in Beijing, weather charts from Korea Meteorological Administration (KMA) and NCEP reanalysis data, the characteristics of the air pollution of Particulate Matter with particle size below 10 μm (PM10) in Beijing and its cause of formation during the 2008 Olympic Games period (from July to September) are analyzed, types of synoptic situations are classified according to being or not helpful to dispersion of pollutants, and typical synoptic situations and meteorological conditions in PM10 air pollution episodes are studied. The results are that: 1) There were eight days with PM10 air pollution in Beijing during the whole period, including a persistent PM10 air pollution. But no PM10 air pollution occurred during the Olympic Games and Paralympic Games, which mainly resulted from more rainfall in August and September of 2008. 2) Synoptic situations not helpful to pollutants dispersion (e.g. south wind with low speed, high air temperature and relative humidity, and persistent vertical inversion in low layer) were frequent, but they did not cause typical PM10 air pollution by a possible reason of the pollution control measures. 3) Most PM10 air pollutions were related with northwestward-moving typhoon or tropical cyclone, which would block synoptic system influencing North China to move eastward.