The invention relates to a light catalysis material, and in particular relates to a method for preparing a graphene-based composite visible light catalysis material. The method comprises the following steps: dissolving graphene oxide into water, so as to obtain a graphene oxide dispersion liquid in an ultrasonic mode; dropping a silver nitrate solution into the graphene oxide dispersion liquid under a stirring condition, and stirring for a certain time to obtain a mixed pecursor solution A; slowly dropping a prepared titanium dioxide solution into the mixed pecursor solution A to obtain a mixed solution B; slowly dropping a prepared phosphate solution into the mixed solution B to obtain a mixed solution C, continuously stirring the mixed solution C for a certain time, subsequently transferring the mixed solution C into a hydrothermal reaction kettle, carrying out hydrothermal reaction at certain temperature, and cooling to be the room temperature; subsequently carrying out centrifuging, washing and vacuum drying on a product so as to ultimately obtain the composite material. The material shows super-high degradation activity to organic dye Rhodamine B under the action of visible light excitation.