Modified Fe-PAN fibrous catalyst (Fe-AO-PAN) was formulated at the room temperature by the reaction of amidoxime (AO) modified polyacrylonitrile (PAN) fiber (AO-PAN) with FeCl₃, which was in turn used as an environmentally friendly heterogeneous photocatalyst in the oxidative degradation reaction of the standard target dye Rhodamine B in the presence of hydrogen peroxide. This paper investigated the influences of the iron ion concentration in solution ( C _Fe ) and reaction temperature to the iron ion content in Fe-AO-PAN catalyst ( C _{Fe-AO ? PAN} ); studied the effects of C _{Fe-AO ? PAN} , pH, intensity of light irradiation and etc. on the decoloration rate of the dye; and analyzed the oxidative degradation procedure of the dye by ultraviolet-visible light spectrum analysis. The results indicate that C _{Fe-AO ? PAN} increases with the rise of C_Fe or reaction temperature; the decoloration rate of Rhodamine B increases with the rise of C _{Fe-AO ? PAN} or radiation intensity, as well as the decrease of initial concentration of the dye; and Fe-AO-PAN shows higher catalytic activity in the solution of pH less than or equal to 6.0, however lower catalytic activity in a strongly basic medium. In addition, ultraviolet-visible light spectrum analysis proves that Fe-AO-PAN can effectively catalyze the break of azo bond and aromatic ring in the dye molecular, but can not be reutilized efficiently.