All-solid-state polymer electrolyte lithium sulfur batteries have shown technical and commercial values due to both high energy density and safety. However, room temperature application of the batteries is limited mainly by low lithium ionic transportation efficiency of the electrolyte. In this study, crosslinked polymer hosted solid electrolyte is developed to address the current issues. Results show that the flexible electrolyte possesses not only high ionic conductivity but also high lithium ion transference number at 25 ^oC. Lithium sulfur batteries fabricated with the electrolyte deliver initial discharge capacity of 1374 mAh g^-1 at room temperature. Additionally, mechanisms for such enhancements are studied by cyclic voltammetry, X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and thermo-gravimetric analysis techniques.