Composite solid electrolytes (CSEs) combining the advantages of both inorganic and organic solid-state electrolytes, are expected to become the most promising solid electrolyte owning to their favorable interfaces with electrodes. However, low room-temperature ionic conductivity restricts the application of CSEs in lithium metal batteries. Herein, we design an intercalated CSE based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). Kaolin (2SiO2-Al2O3-2H2O), employed as an oxidative flame retardant, imparts nonflammability to the material. The polar molecule dimethyl sulfoxide (DMSO) is inserted between the kaolin layers as the pre-intercalation treatment, serving as an organic additive within the PVDF-HFP based SPE. The intercalated structure of CSE provides rapid Li+ transport channels, resulting in a high ionic conductivity (8.58 × 10−4 S cm−1) and large Li+ transference number at room temperature. The Li||Li symmetrical cell with prepared CSE exhibits outstanding