Abstract: The nanoparticles of magnesium ferric layered double hydroxides(Mg-Fe-LDHs) were synthesized by coprecipition method, and their shape, chemical composition, crystal structure, anion exchange capacity and the effects of the n(Mg): n(Fe) in raw material on these properties were studied by transmission electron microscope, chemical analysis and X-ray diffraction etc.. It was found that the Mg-Fe-LDHs particles were plate like nanoparticles, and their chemical compositions are basically consistent with the compositions of raw materials. In the range of n(Mg): n(Fe) of 2:1～4:1, the Mg-Fe-LDHs has the same layered crystal structure as hydrotalcite which belongs to the hexagonal system. With increasing of n(Mg): n(Fe) in the chemical compositions of the samples from 2:1 to 4:1, the particle size of the samples increases from 37.9 nm to 61.2 nm. The lattice constant, a, of hexagonal cell decreases from 0.317 nm to 0.310 nm and the lattice constant, c, of hexagonal celLIncreases from 2.380 nm to 2.412 nm. The basal spacing of the Mg-Fe-LDHs increases from 0.793 nm to 0.804 nm. The anion exchange capacity of the Mg-Fe-LDHs increases from 0.52 mmol/g to 1.82 mmol/g.

Key words: Coprecipitation method, Nanoparticle, Layered double hydroxides, Anion ex-change capacity, Hydrotalcite-like compounds