Bismuth iodide oxide (BiOI) has attracted attention in the fields of photocatalysis, photovoltaics and photodetectors due to its low toxicity, tolerance to point defects, and strong light absorption ability. This article adopts the chemical vapor deposition (CVD) method, using BiI3 powder as the evaporation source and O2/Ar as the reaction gas, to obtain high c-axis oriented BiOI films on a soda-lime glass substrate. The growth mechanism of BiOI films was analyzed by studying the effects of evaporation source temperature and deposition time on the phase and morphology of the films. The results indicate that the BiOI films prepared by CVD method belongs to the tetragonal crystal system with a high c-axis orientation. The c-axis oriented thin film grows parallel to the substrate, the evaporation temperature and deposition time have a significant impact on the crystallization, absorption ability and traps of the BiOI films. When the evaporation temperature is 370 ℃ and the deposition time is 20 min, the BiOI film has the best crystallization and the lowest transmittance and traps.