Abstract: With the development of polymer materials science and technology, widely used polymer materials such as plastics and rubber have received increasing attention due to their poor flame retardant performance and susceptibility to fire. Flame retardant materials have the characteristics of high temperature resistance, reduced combustion generation, reduced flame propagation speed and smoke volume. Ionic liquids (ILs) have become a new type of flame retardant material due to their high thermal stability, gas-phase flame retardancy, and ability to suppress free radicals. Due to its controllable structure of anions and cations and environmental friendliness, it has gradually been applied in the field of flame retardancy. This article briefly introduces the types, preparation methods, and flame retardant mechanisms of ionic liquids. Then, a detailed introduction is given on the flame retardant applications of ionic liquids in various polymer materials such as polymers, textiles, and electronic materials. Finally, the development of ionic liquids in flame retardant applications is discussed.