In this paper, the Sb2O3 nanoparticles prepared with SbCl3 by the alky hydrolysis, processed with the surfactants, were assembled on mica substrates. The morphology and the assembled behavior of the nano-Sb2O3 on the mica were analyzed by means of TEM. The flame retardant properties of nano-Sb2O3 and Sb2O3/mica complex were studied by combustion test and thermal analysis. The results show that the Sb2O3 nanoparticles are assembled uniformly on the mica substrates. The nano-Sb2O3 was characterized with small size, narrow size distribution, uniform crystal and monodispersed particles. Compared with nano-Sb2O3, the Sb2O3/mica complexes have been achieved the same coordinated effects with Chlorinated Paraffin(CP) and excellent flame retardant properties.