Abstract: The slope model of the Yimin open pits was established and solved by FLAC program.Then the deformation and stress of the end wall was analyzed,and the results of no internal dumping was compared with those of internal dumping.Then the maximum stable angle of the end wall was calculated.The results demonstrated that the internal dumping could decrease the deformation of the end wall in the open pits and improve its stability,and increase its maximum stable angle at the same safety factor.So,using the internal dumping could decrease the waste volume or increase the production,reduce the stripping ratio,and improve the economic benefit.