The invention discloses a 
bismuth compounded 
bismuth oxyiodide photocatalyst containing 
iodide ionic defects and a preparation method of the 
bismuth compounded bismuth oxyiodide photocatalyst. The bismuth compounded bismuth oxyiodide photocatalyst containing the 
iodide ionic defects is prepared through 
precipitation, centrifugal washing, magnetic stirring and other steps. According to the bismuthcompounded bismuth oxyiodide photocatalyst containing the 
iodide ionic defects and prepared with the method, a plurality of defect intermediate levels are formed between a 
valence band and a 
conduction band of the photocatalyst by constructing the iodide ionic defects, excitation and transmission paths of photo-induced electrons are changed, migration and transformation of photo-generated chargesare promoted, and recombination of photo-induced 
electron-hole pairs is inhibited. Visible 
light response range is enlarged, visible light 
utilization rate is increased, and finally, the 
NO removal rate of the prepared bismuth compounded bismuth oxyiodide photocatalyst containing the iodide ionic defects is increased. Besides, economic cost for producing the bismuth compounded bismuth oxyiodide photocatalyst containing the iodide ionic defects and prepared with the method is low.