Global warming has caused non-uniform changes in precipitation intensity and distribution, which will inevitable impact on the wet and dry climate. In order to make clear the distribution of dry-wet climate zone and changes have occurred in recent 54 years, authors analyzed the temporal and spatial variation characteristics of dry and wet climate in North China Plain over the period 1961 to 2014 in this paper. The influence of main meteorological factors on ET_0 was also been studied by using the sensitivity and contribution rate method, as well as the causes for dry-wet climate variation. In this study, 62 meteorological stations each with 54-year data record (from 1961 to 2012) were selected in China (including Beijing, Tianjin, Shandong, Henan and Hebei), ET_0 was then calculated by using Penman-Monteith method. The results showed that the area of semi-arid area was expanding continuously since the dividing line for semi-arid area and semi-humid area extended eastward and southward in three periods (period 1:1961-1980; period 2:1981-2000; period 3:2001-2014). However, the humid area did not show significant changing trend. Precipitation showed non-significant trend over the period 1961 to 2014, while ET_0 showed a significant decreasing trend with large spatial differences. In most parts of Henan and Shandong, the climate became wet because that the negative trend for ET_0 is larger than the decreasing trend for precipitation. On the contrast, most of Tianjin and Hebei regions showed significant dry trend rates with the decreasing precipitation and increasing ET_0. As for the main contribution factor to ET_0 changes in each month, wind speed was the dominant factor in November to the following January, temperature in February, and sunshine hours in June to September. The main contribution factors to ET_0 in other months were result from the combined effects of relative humidity and wind speed.