Two ensemble simulations for 22 boreal-summer seasons (1979-2000) are conducted by the Community Atmosphere Model version 3 (CAM3) with the specified observed sea surface temperature(SST).Impacts of surface soil moisture(SSM) on the simulation of potential predictability of East Asian summer climate are investigated by the model with interannually varying SSM(ISSM) and climatological SSM(CSSM),respectively,based on the variance analysis method.Results show that,under the specified observed SST,the potential predictability of East Asian summer climate simulated by the CAM3 with ISSM is better than that with CSSM over East Asia,especially over Northwest China.The potential predictability of summer precipitation and air temperature over Northwest China from ISSM simulations is 0.1 higher than that from CSSM simulations.A possible mechanism of influence of soil moisture on potential predictability of summer climate in Northwest China is proposed.The interannual variability of ground evaporation and surface turbulent heat flux can be simulated by CAM3 with ISSM better than with CSSM in Northwest China,leading to the model forecast skill of the summer climate improved by the model with ISSM.