The invention discloses a preparation method and application of a chitosan bi-metal complex catalyst. The preparation method comprises the following steps: dissolving chitosan in an acetic acid solution; slowly adding a ferric chloride solution and copper sulfate mixed solution for stirring at room temperature; adding an organic solvent, and then separating out a solid; conducting filtration, washing and drying on the solid to obtain the chitosan bi-metal complex catalyst. The prepared chitosan bi-metal complex catalyst and a method for removing dye pollutants in water by use of the chitosan bi-metal complex catalyst are simple to implement, friendly to environment and low in cost, and the effect of removing the dye pollutants in water is good, so that the method can serve as an environment-friendly efficient dye wastewater treatment method.