Based on the background of global climate changes, distribution of arid and humid area has been changing in China. In order to understand the impacts of climate changes on China, this paper analyzed the dynamic changes of wet and dry areas of China during the past 60 years(1951-2010)based on climate data from 756 meteorological stations. Potential evaporation was calculated using Penman-Monteith method. Combined with precipitation data, aridity index for 1951 to 2010 was calculated. Based on the threshold of aridity index of wet and dry areas, six wet and day zones were divided, including hyper-arid, arid, semi-arid, dry sub-humid, sub-humid, wet sub-humid, and humid zones. The dynamic changes were analyzed per decade. Our results show that the majority area of China tends to be dry, particularly Northeastern China. Northern Xinjiang Autonomous Region tends to be wet. During the year of 1951 to 2010, the ten years' changes had been different during different period. Wet period is 1980s. A period of extreme drought is 1990s. The range of semi-arid zone has increased. Our results are useful for understanding spatial distribution of vegetation and ecological environment construction.