The uncontrollable dendrite lithium growing is a hazardous behavior for lithium metal batteries, which is mainly cause for restraint of its commercial applications. Gel-based polymer electrolyte is emerging as a promising solution to achieving high ionic conductivity dendrite-free lithium deposition and good safety for developing high-performance all-solid-state rechargeable batteries. In this work, a new sponge-supported gel-based polymer electrolyte is developed by in-situ gelation of precursor solution-soaked (1,2-diacrylyl ethane, 2,4,6-triallyloxy-1,3,5-triazine and LiPF6 electrolyte) commercial sponge. In the sponge-supported polymer electrolyte, commercial sponge is served as the supporting framework to dissipate energy, enhancing mechanical strength of polymer electrolyte, while the cross-linked 1,2-diacrylyl ethane and 2,4,6-triallyloxy-1,3,5-triazine contained LiPF6 electrolyte endow fast ion transmitting for polymer electrolyte. The S-GPE with compact structure is conducive to be formation of a highly uniform and robust SEI layer on the lithium metal, thus resulting in remarkable lithium dendrite-resistance and electrochemical performances (ionic conductivity, interfacial resistance, charge/discharge, rate behavior, and long-term cyclic lifespan).