Layered double hydroxide （LDH) is a typical anionic layered material with excellent flame retardancy and thermal stability, low smoke, low toxicity and environmental friendliness. The preparation of composites by combining LDH with polymers can significantly improve the fire resistance of polymers, which has attracted wide attention of researchers. This paper introduces the structural characteristics, organic modification methods of LDH including ion exchange method, calcination-reconstruction method, one-step method and solvent exfoliation method. The methods commonly used in the preparation of polymer/LDH composites are summarized and also briefly describe their advantages and disadvantages. Furthermore, the factors affecting the flame retardancy of polymer/LDH composites are reviewed, including the effects of LDH ply bivalent and trivalent cations, the introduction of polymetallic cations and modifiers. A brief description of the progress of other flame retardant materials in combination with LDH using synergistic flame retardant. Finally, the author analyzes the research status of flame retardant polymer/LDH composites. The viewpoints of industrialization of polymer/LDH composites, improvement of flame retardant efficiency and clear flame retardant mechanism were put forward.