Abstract: Expanded vermiculite/phenolic flame retardant and insulation composites were prepared by compounding expanded vermiculite as a flame retardant and phenolic resin via a medium temperature foaming method. The effects of foaming temperature, content of curing agent, content of foaming agent, content of surfactant, curing time and content of expanded vermiculite on flame retardant and thermal insulation performances of expanded vermiculite/phenolic flame retardant and insulation composites were analyzed by limit oxygen index, cone calorimetry, thermal conductivity and apparent density. The results show that expanded vermiculite/phenolic flame retardant and insulation composites prepared by expanded vermiculite as a flame retardant show good flame resistance, good insulation and low apparent density. The results of single factor experiment show that the optimized conditions of expanded vermiculite/phenolic flame retardant and insulation composites are that the foaming temperature is 80℃, content of curing agent is 10wt%, content of foaming agent is 10wt%, content of surfactant is 5wt%, curing time is 2 h and content of expanded vermiculite is 60wt%, under which, the apparent density of expanded vermiculite/phenolic flame retardant and insulation composites is 190.08 kg/m³, the compressive strength is 0.32 MPa, the thermal conductivity is 0.054 9 W/(m·K), the limit oxygen index is 71.1%, the average heat release rate is 15 kW/m².