The invention discloses a sodium bismuthate/epoxy resin/glass fiber composite material, a preparation method thereof and an application method for the composite material in degradation of organic waste water. The preparation method comprises the following steps: soaking sodium bismuthate powder in an aqueous solution of a silane coupling agent for treatment, then taking out the sodium bismuthate powder and drying the sodium bismuthate powder for subsequent usage; adding methyl tetrahydrophthalic anhydride into an epoxy resin and carrying out uniform mixing so as to obtain an epoxy resin glue solution; and mixing the treated sodium bismuthate with the epoxy resin glue solution, carrying out ultrasonic dispersion, coating an obtained mixture on glass fiber cloth, folding the glass fiber cloth three to five times in a die, carrying out curing, cooling and demolding and cutting the glass fiber cloth to a certain shape and a certain size. The application method comprises the following steps: uniformly putting the composite material with an appropriate shape and an appropriate size between jacket layers of a glass tube reactor and installing a visible light lamp at the center of an inner tube; allowing organic waste water to enter into a glass jacket, pass through the composite material and undergo a visible light catalytic degradation reaction with sodium bismuthate under irradiation by visible light. The preparation method has the advantages of low requirements on equipment, simple procedures, low energy consumption and convenience in operation; and the composite material is capable of degrading organic waste water in a short period of time.