The invention relates to chitosan coated bauxite printing and dying industry wastewater flocculating agent and preparation method thereof, relating to the water treatment medicament technical field. Chitosan, natural bauxite and industrial hydrochloric acid are taken as raw materials, are mixed and stirred by ratio and sequence and then are subject to baking or microwave drying, thus obtaining the composite flocculating agent product. Deacetylated degree of chitosan is more than 70%, the fineness of the natural bauxite is 200 meshes, and the ratio of the chitosan and bauxite is 1:10-15(g/g). The main raw material of the invention is natural bauxite and can be reused, cost is low, preparation process is simple, and decolouring effects on active dye, reducing dye, dispersing dye, direct dyeand sulphide dye are all good. The invention has the characteristics of economy, high efficiency, no secondary pollution and environmental protection.