It this paper,based on the data of apparent electrical resistivity ob-served in the regions surrounding some large earthquake (M ≥ 7) epicenters,the influences of rock mechanical properties in the observational region on precursor △ρ_s/ρ_s of apparent electrical resistivity are studied.The resul-ts obtained show that the thickness of quaternary covering soil can abate the precursor of apparent electrical resistivity,and the thicker the quater-nary covering soil,the smaller the value of precursor △ρ_s/ρ_s of apparent electrical resistivity.Moreover,the rocks with loose structure reflect the earthquake qrecursor of apparent resistivity more obviously than that with compact structure.Therefore,the observational stations of apparent electrical resistivity must be installed on the thin soil layer covered the rock fundament with low electrical resistivity.