In this paper, we report a low-temperature solution method to deposit thio-LISICON, Li3.25Ge0.25P0.75S4, thin film. The low-temperature solution-processed Li3.25Ge0.25P0.75S4 film shows a lithium-ion conductivity of 1.82 × 10−4 S cm−1 at 30 °C, an activation energy of 0.42 eV, and a lithium-ion transference number of >0.999, which might be applicable in thin film all solid state lithium-ion batteries.