In order to appraise the west-slope stability at the Huidong Surface Mine, a considerable number of rock mechanics experiments both in laboratory and situ have been taken.The experiments include those on shear strength of rockmass and rock structure planes, rockmass elastic modulus, rockmass stress and strain, etc.The results from the tests and the comprehensive analyses indicate that the black fracture rockmass and weak structure planes are the main influence factors on the westslope stability at the mine, however, the siliceous dolomite zone in the black fracture rockmass has relatively better integrity and can play a certain control function for stability of the wallrocks and slope.