The improved ionic conductivity (1.64 × 10–4S cm–1at room temperature) and excellent electrochemical stability of nanoporous β-Li3PS4make it one of the promising candidates for rechargeable all-solid-state lithium-ion battery electrolytes. Here, elastic properties, defect thermodynamics, phase diagram, and Li+migration mechanism of Li3PS4(both γ and β phases) are examined via the first-principles calculations. Results indicate that both γ- and β-Li3PS4phases are ductile while γ-Li3PS4is harder under volume change and shear stress than β-Li3PS4. The electrochemical window of Li3PS4ranges from 0.6 to 3.7 V, and thus the experimentally excellent stability (>5 V) is proposed due to the passivation phenomenon. The dominant diffusion carrier type in Li3PS4is identified over its electrochemical window. In γ-Li3PS4the direct-hoppingof Lii+along the [001] is energetically more favorable than other diffusion processes, whereas in β-Li3PS4the knock-offdiffusion of Lii+along the [010] has the lowest migration barrier. The ionic conductivity is evaluated from the concentration and the mobility calculations using the Nernst–Einstein relationship and compared with the available experimental results. According to our calculated results, the Li+prefers to transport along the [010] direction. It is suggested that the enhanced ionic conductivity in nanostructured β-Li3PS4is due to the larger possibility of contiguous (010) planes provided by larger nanoporous β-Li3PS4particles. By a series of motivated and closely linked calculations, we try to provide a portable method, by which researchers could gain insights into the physicochemical properties of solid electrolyte.