Abstract: Abstract: Based on the daily precipitation data of 308 observational stations in the 15 provinces of the northern region of China during 1961-2010, we divided the northern China into 3 zones (arid, semi-arid and semi-humid) according to the 200 and 400 mm isohyets. In this research, the year 1981 was taken as a time node to divide the period from 1961 to 2010 into 2 sub-periods. We figure out the spatial variation of the 3 zones between the 2 sub-periods. The numbers of the days of light, moderate, heavy and torrent precipitation grades were calculated, and their distribution characteristics in each season were studied. Meanwhile, we also analyzed the frequency and intensity of each precipitation grade and its contribution to the annual rainfall. The main conclusions were listed as follows: as the change of rainfall, the semi-arid zone expanded significantly in the research region since 1981 but the semi-humid zone in Northeast China and the arid zone in the southeast of Northwest China decreased. During the recent 50 years, the annual rainfall increased in arid zone, while the rainy days decreased in semi-arid and semi-humid zone. All precipitation indices at different grades in the second period (after 1981) were higher than those in the first period, especially at light and moderate grades in the north. The most obvious seasonal variation in arid zone happened in the winter. The summer and autumn precipitation in the second period was less than that in the first period in semi-arid and semi-humid zone. It was worthy to note that the precipitation in semi-arid zone significantly decreased in summer, while in autumn occurred the remarkable seasonal precipitation variation in semi-humid zone. The frequency of light and moderate rainy days to the annual rainy days in the northern region was more than 95%, while the contribution of light and moderate rainfall to the annual rainfall was 75%; although the frequency of moderate rain was less than the light rain, it had a remarkable upward trend and the frequency of light rain was in a downward trend, especially in the arid zone, so the efficiency of precipitation for crops in growing season was less affected. In arid area, the contribution of rainfall in spring was on the rise and the frequency of rainy days in summer was on the opposite. In the semi-arid zone, the contribution of rainfall in spring also increased, what's more, the seasonal change of rainfall frequency was very evident that the frequencies of rainy days in spring and winter increased and those in summer and autumn decreased. In addition, the frequency of rainy days in spring and winter also improved in the semi-humid zone, and the most obvious change in the semi-humid zone happened in autumn where the amount of rainfall and rainy days declined. The fluctuations of rainfall in summer and autumn or extreme precipitation events prone to occur may adversely affect the crop growth in the region. The extreme value for each precipitation index mainly was concentrated at the north and south ends of those 3 zones. The amount and frequency of heavy rainfall in the northern part of Xinjiang and Inner Mongolia were larger than those in the Qinghai, Gansu and Ningxia. This study is important for quantifying the situation of precipitation resources in the areas with different arid and humid conditions in northern region of China, which is helpful for the adjustment of planting structure and crop layout.