The characteristics and causes of the spatio-temporal variation of the EASM precipitation on centennial time scale were analyzed in this paper based on the climate simulation results over the past 2000 years using the Community Earth System Model (CESM). It has an important scienjpgic significance to recognize the climate change on centennial time scale and to distinguish the influence of external forcing on the EASM. The results show: ①The East Asian Summer Monsoon (EASM) precipitation and temperature mainly reflect an in phase variability on centennial time scale. We found that there are three periodicities (100a, 150a and 200a) in the EASM precipitation. ②The spatial structures of the first mode of the standardization EOF of the EASM precipitation show the “minus-plus-minus-plus” zonal belts while the spatial structures of the second mode show almost an in phase variability in the East Asian region. ③The 100 year cycle of the EASM precipitation is caused by the total solar irradiation, the volcanic eruptions and the internal variability of climate system. The 150 year cycle is caused by the total solar irradiation and the 200 year cycle is caused by the total solar irradiation and the volcanic eruptions. The main cause of the spatial patterns of precipitation in the East Asian region is the total solar irradiation but forcings affect differently in different latitude. The factors affecting the spatial change of the extratropical EASM precipitation are the greenhouse gases and the land use and land cover change, while the factors affecting the spatial change of the subtropical EASM precipitation are the total solar irradiation and the volcanic eruptions. And the factors affecting the spatial change of the tropical EASM precipitation are the total solar irradiation, the volcanic eruptions and the internal variability of climate system.