Zn/Al/W(Mn) mixed oxides were prepared via calcination of the precursors of monovacant and monosubstituted Keggin type polyoxometalate (POM) intercalated layered double hydroxides (LDHs) such as Zn2Al(OH)6-[SiW11O39]0.12 • 0.2H2O and Zn2Al(OH)6[SiW11O39Mn(H2O)]0.16 • 0.3H2O at 600-700℃. The physicochemical properties of the products were characterized by the methods of powder X-ray diffraction, elemental analysis, scanning electron microscopy, UV diffusion reflectance spectroscopy, infrared spectroscopy, thermogravimetric analysis, electron spin resonance and N2 adsorption-desorption measurements. Phase changes during the process of calcination of the POM containing LDH precursors were studied, indicating that the precursors decomposed at 400℃ and formed ZnO and Al2O3-like phases together with an X-ray amorphous phase, and then yielded a mixture of well-crystallized phase of ZnAl2O4 formal spinel and ZnWO4 inverse spinel at 600-700℃. As for the thermally decomposed products, the changes of BET surface areas and pore sizes are related to their crystallinity and structures. Compared with the POMLDH precursors, the mixed oxides thus obtained exhibited higher photocatalytic activity to degrade aqueous organochlorine pesticides hexachlorocyclohexane.