Thermal initiation polymerization was used and optimized to prepare poly(methyl methacrylate) gel polymer electrolytes (PMMA-GPE). The impact of vinylene carbonate (VC) on the electrochemical performance of mesophase-pitch-based carbon fibers in PMMA-GPE for lithium-ion batteries was investigated using cyclic voltammetry (CV), linear sweep voltammetry (LSV) and charge–discharge test. As expected, adding VC with a proper concentration of 1 vol% into GPE results in better electrolyte conductivity, cycling performance, and reversible capacity. Combining with Scanning electron microscopy, LSV and CV, detailed EIS investigation was used in order to better understand the modified mechanisms of graphite electrode in GPE with VC. The results reveal that the improvement of electrochemical performance is mainly due to the effective inhibition on growth of the internal resistance, which mainly attributed to the solid electrolyte interphase with an electrochemically and structurally stability mainly formed by the reduction and polymerization of VC at higher potential as restraining the side reaction of the reduction and polymerization of matrix in GPE.