The effects of applied pressure on the structural, mechanical, and electronic properties of LaAg5 compound were investigated employing the first-principles method based on the density functional theory. The mechanical results demonstrated that bulk modulus, shear modulus and Young’s modulus presented the linearly increasing dependences on the external pressure; the B/G and Poisson’s ratio indicated that La Ag5 compound was a ductile material with central forces in interatomic under pressure from 0 to 40 GPa; the universal anisotropic index was performed to investigate the elastic anisotropic of La Ag5. Additionally, the pressure dependence of the density of states and Mulliken charge were also discussed. The bonding characterization in La Ag5 was composed of metallic, covalent and ionic. The metallic component was derived from free-electron transferring from Ag-s and Ag-d to Ag-p, and from La-s to La-d. The ionic component was due to the charge movement from La to Ag. The covalent was owing to Ag-p-La-d bonding hybridization and Ag-s-Ag-p in the Ag atomic chains. The covalent and ionic bonds were stronger under pressure but there was no significant change in metallic nature. The effects of applied pressure on the structural, mechanical, and electronic properties of LaAg5 compound were investigated employing the first-principles method based on the density functional theory. The mechanical results of the bulk modulus, shear modulus and Young’s modulus presented the linearly increasing dependences the B / G and Poisson’s ratio indicated that La Ag5 compound was a ductile material with central force in interatomic under pressure from 0 to 40 GPa; the universal anisotropic index was done to investigate the elastic anisotropic of La Ag5 The pressure dependence of the density of states and Mulliken charge were also discussed. The bonding characterization in La Ag5 was composed of metallic, covalent and ionic. The metallic component was derived from free-electron transferring from Ag-s and Ag-d to Ag-p, and from La-s to La-d. The ionic component was due to the charge movement from La to Ag. The covalent was Due to Ag-p-La-d bonding hybridization and Ag-s-Ag-p in the Ag atomic chains. The covalent and ionic bonds were stronger under pressure but there was no significant change in metallic nature.