The PM2.5 mass concentration data from Baolian Atmospheric Composition Monitoring Station, which represents urban area, in 2005-2014 and the data from Shangdianzi BAPStation, which represents rural area, from 2006 to 2014 are used to analyze its longterm temporal evolvement in Beijing. The results show that the PM2.5 pollution was the severest during 2005-2007. Since 2008, the annual mean mass concentration and the days of moderate pollution or over have been reduced, but the situation became worse from 2013 to 2014. The average mass concentration in urban area was the highest in winter and autumn, and took the second place from spring to the early of summer. However, in recent several years, such pollution tends to be reduced somewhat in spring and summer. At the same time, high mass concentration was found more often in autumn, which enlarges the seasonal gap. One impact factor is the sanddust weather in spring. At Shangdianzi Station, the rural area, the annual mean mass concentration is higher in spring and summer, different from that in urban area. But since 2011, the above difference has become much smaller. This indicates that the regional pollution takes place more commonly. On average, there are 30 pollution days at moderate level, 26 days at severe level and 4.7 days at extreme level every year. However, there is some monthly and annual discrepancies of this characteristic. Besides, the moderate pollution cases decreased while severe ones increased in 2013 and 2014. Therefore, the annual mean mass concentration has higher relationship with the severe pollution events in winter and autumn. The moderate or severe pollution days in Shangdianzi are only 1/3 of that in urban area. Moreover, the persistent pollution event appears in winter and autumn normally. The annual average times of pollution events which last at least 3 days are 1.9 for moderate level and 0.6 for severe level during 2008-2014. Most extreme events could cover 2 to 3 days only. Based on the statistics, the mass concentration often reaches severe grade or above after the middle stage of the event. So, it might reduce the possibility of severe pollution by controlling emission in advance when the meteorological condition is not favorable for the diffusion of pollutants.