The safety issues of lithium batteries caused by liquid organic electrolyte have been driving people to seek safer solid-like electrolytes. Herein, we report effort to employ Polyurethane acrylate (PUA) elastomer and Succinonitrile (SN)-based plastic crystal electrolyte (PCE) to fabricate a composite PCE (CPCE) by solution blending followed by rapid UV curing. During fabrication process, the phase separation between PUA and SN-based PCE can be suppressed by adding Tetrahydrofuran (THF). Consequently, the improved compatibility results in an improved mechanical strength in the CPCE and makes PUA impart the good stretching and resilient properties to the CPCE. The optimized CPCE presents a maximum stretching strain of 90.6% and can bear cyclic stretching-releasing test. Besides, the CPCE exhibits a high ionic conductivity of 0.91 × 10−3 S cm−1 at 30 °C and a wide electrochemical stability window of 4.8 V. Thus, this stretchable CPCE could be used in flexible batteries for emerging applications such as wearable electronic devices and flexible sensors.