This paper aims to study physical properties of autoclaved aerated concrete of fly rice husk ratio replace the sand: 5, 10, 15 and 20 %, by mix autoclaved aerated concrete non dry, dry fly rice husk temperature 75 and 105 oC, and studying microstructure by using scanning electron microscope (SEM) of autoclaved aerated concrete of fly rice husk and autoclaved aerated concrete to commercialization. From the study, it indicated that autoclaved aerated concrete cause non dry fly rice husk mix 5 % which can produce qualified autoclaved aerated concrete as they can bare 5.35 N/mm2 of compressive strength, 23.80 ksc of flexural strength, 645.30 g/cm3 of density and 0.38 g/cm3of absorption water. Case dry fly rice husk temperature 105 oC mix 20 % which can produce qualified autoclaved aerated concrete as they can bare 5.16 N/mm2of compressive strength, 26.80 ksc of flexural strength, 647.88 g/cm3of density and 0.40 g/cm3of absorption water. Microstructure by using scanning electron microscope (SEM) at 3500X magnification its found that there had the same result orthorhombic structure formed the strength strength of autoclaved aerated concrete of fly rice husk.