To investigate the atomic-scale structural origin of the Vickers hardness (HV) and glass transition temperature (Tg) of peraluminous aluminosilicate glasses with alkaline earth ions, we prepared a series of xRO·(49-x)Al2O3·51SiO2 (x=0.0-16.0, in mole fraction; R=Mg, Ca, Sr, Ba) alkaline earth aluminosilicate glassy samples. HV and Tg were characterized by Vickers micro-hardness test and differential scanning calorimetry (DSC). The results show that HV increases, while Tg decreases with the increase of R2+ field strength at a fixed RO content. At a certain type of RO, HV and Tg decrease simultaneously with the gradual substitution of Al2O3 by RO. 49Al2O3·51SiO2 glass has the maximum HV (i.e., 8.26 GPa) and Tg (i.e., 941 ℃). According to the structural analysis, the interactions between the competition and synergism among the packing density, average bond energy, bond energy density of glass network skeleton ions and the interstitial ions as a charge balancer are a main atomic-scale structural origin, thus leading to the reverse evolution of HV and Tg with the increase of field strength of substituted R2+ and the similar change with the substitution of RO for Al2O3 in peraluminous aluminosilicate glasses.