Polyacrylic acid/attapulgite (PAA/ATP) nanocomposites were prepared by copolymerization of acrylic acid and the modified attapulgite which was obtained by γ-methacryloxy propyl trimethoxy silane(KH-570) modifying. The results showed that PAA/ATP nanocomposite was successfully obtained, and the ATP in PAA/ATP nanocomposite can be uniformly dispersed. The appearance stability and thermal stability of PAA/ATP nanocomposites were the optimal when When the amount of ATP in acrylic acid（AA）was 1%. It indicated that the flame retardancy and thickening properties of the leather had improved when the PAA/ATP nanocomposite was applied to the retanning process of wet blue sheep leather. Meanwhile, the flame retardancy of the leather after the retanning of the PAA/ATP nanocomposite was the optimal when the amount of ATP in acrylic acid（AA）was 1%.