A reversible strong photochromic phenomenon in spiro oxazine (SO) dye doped polyvinyl alcohol (PVA) films is reported. The absorption spectrum of the SO/PVA film shows that there are two characteristic absorption bands at 360 nm and 595 nm, which correspond to the two different molecular configurations SO 1 and SO 2, respectively. Then temporal behavior of the photo isomerization between the two molecular configurations is also investigated. The molecular absorption coefficients of SO1 to UV light and SO2 to the probe beam at 515 nm are found to be 1.2 cm2/J and 6×10-2 cm2/J, respectively. The life time of SO2 in dark is about 38 seconds. Spatial light modulation and UV-to-visible image conversion using this photochromic film are demonstrated experimently.