Abstract: Ca（NO₃）₂·4H₂O，Al（NO₃）₃·6H₂O，NaOH，and H₃BO₃ were selected as raw materials to synthesize calcium and aluminum layered double hydroxides（Ca-Al-LDHs） intercalated by boric acid radical using an ion-exchange method，and the products were characterized by XRD，SEM，and FT-IR.The results indicated that the product had good layered structure， the flaky crystals of it were observed and the intercalated boric acid radical in the product included BO₄^5- and BO₃^3- two types of structures. Stearic acid and silane coupling agent （DNZ-311） were selected as modifiers to modify the synthesized product. Then the modified product EVA composite was prepared and the oxygen index of the composite was tested to investigate the flame retardancy of LDHs.The EVA composite doped with 40% of modified Ca-Al-LDHs intercalated by boric acid radical exhibited a tensile strength of 9.68 MPa，an average breaking elongation of 663.3% and a limit oxygen index of 27.2%.

Key words: LDHs, Ca-Al-LDHs intercalated by boric acid radical, EVA, mechanical properties, flame retardancy