Understanding interglacial climate diversity and intra interglacial variability can help assess the sensitivity of the Earth system to different forcing and help assess the rate and magnitude of current climate change relative to natural variability. This study examines the individual and combined effects of astronomical parameters (obliquity, precession, and eccentricity), Greenhouse gases (GHG) concentrations and ice sheets on the East Asian climate during the last nine interglacials by simulations with an atmosphere-ocean coupled general circulation model HadCM3. Results show that the general impacts of astronomical forcing, GHG and ice sheets on the regional climate in East Asia are similar among the interglacials but have different intensity. Vertical dynamic component is the primary contributor to the boreal summer precipitation change in the East Asian summer monsoon domain, and vertical thermodynamic component is the secondary one. Horizontal meridional dynamic component and zonal thermodynamic also have positive effects on the summer precipitation. All the four key components are significantly correlated with precession. Astronomical and GHG forcings both have positive effects on the summer temperature and precipitation. Within the range of its variability during one interglacial, CO2 can cause similar degree of warming effect but much lower degree of humidifying effect as compared with insolation. Insolation and GHG affect the precipitation by dynamic and thermodynamic processes, respectively. Compared with the dominant role of insolation, ice sheets just modulate the magnitude of the East Asian summer monsoon's response to insolation. In 20°N-30°N, ice sheets reinforce summer precipitation regardless insolation when their volume is below a threshold. In 30N°-35°N, ice sheets reinforce summer precipitation regardless their volume when insolation is below a threshold. The comparison of the nine interglacials show that their intensity and internal variability have strong regional diversity in East Asia.