To understand the physical factors determining the material properties is of essential importance for the synthesis of new compositions with favorable characteristics. So far the relationship between the electronic structure and the physical properties of metallic glasses (MGs) has not been adequately studied. This project aims to understand and demonstrate the correlation between thermal and mechanical properties of MGs from the viewpoint of valence electron density (VED) in order to provide guidelines for the future design of new systems with desired plasticity. Initially, the thermal and mechanical properties of MGs are explored. A number of MGs were prepared and their amorphous structures were verified by experimental and computational methods. The X-ray diffraction (XRD) and electron diffraction both indicate that there indeed exist short-to-medium-range orders in the amorphous structure. Molecular dynamics simulation confirms the existence of such orders, and also suggests that the amorphous structure consists of diverse polyhedral types, among which some types are dominant (e.g., icosahedral and bee clusters in TisoCuso). These clusters form a five-fold symmetry in the medium range distance. The thermal properties of MGs were studied by continuous differential scanning calorimetry (DSC). For each glassy alloy, the glass transition temperature, and the width of the glass transition region exhibit dependence on heating rate, i.e., they increase with an increase in heating rate; in contrast, the heat enthalpy at crystallization appears to be independent of heating rate, except for the Zr-based sample likely due to its unique crystallization processes. Nevertheless, the larger glass transition temperatures generally correspond to the larger heat enthalpy and the wider glass transition region. Instrumented nanoindentation was performed on MGs to characterize the mechanical properties, in particular at various loading rates and indent sizes. For the La- and Zr-based specimens, the pile-up height and the shear band zone size imaged by atomic force microscopy (AFM) were found to be independent of loading rates, in good agreement with the absence of loading rate dependence of mechanical properties. However, they both show the indentation size effect (ISE), specifically, the hardness is enhanced at smaller indents. In contrast, for CU49.3ZrSO.7, the mechanical properties are influenced by the loading rate, i.e., they increase as the loading rate increases up to a critical value. However, it does not have an ISE. The degree of structural relaxation, which can be represented by the relaxation time spectrum, accounts for the mechanical response of MGs to the loading rates. This spectrum was derived from the nanoindentation creep, and reveals that the Zr-based specimen is in a more relaxed state than CU49.3ZrSO.7 because the former has lower peak intensity than the latter. In other words, the Zr-based specimen is less viscoelastic than CU49.3ZrSO.7. Based on the experimental work, a proportional relationship between thermal and mechanical properties has been identified, which can be determined by the valence electron density-the number of valence electrons per atomic volume. Furthermore, the plasticity or the Poisson's ratio is found to be dependent on VED as well. For each type of MGs, the Poisson's ratio commonly decreases as VED increases. From the energy dissipation viewpoint, the lower shear-transformation-zone (STZ) activation energy implies the higher ductility because STZs with lower activation energy are able to convert deformation work more efficiently into the configurational energy rather than heat. The smaller VED implies a weaker atomic bonding and also easier atomic motion for STZ activation and crystallization. Therefore, the VED-related plasticity suggests a simple method for designing ductile MGs.