The invention discloses a Fe3O4/MoS2/BiVO4 material preparing method, a product and an application of the product. The method comprises the steps: firstly, dissolving ferric chloride hexahydrate, sodium acetate and polyethylene glycol in ethylene glycol, carrying out a reaction at the temperature of 180-200 DEG C for 8-9 h, and thus obtaining ferric oxide; then, mixing sodium molybdate dehydrate,sodium molybdate tetrahydrate and thiourea evenly, adding ferroferric oxide, and carrying out a reaction for 22-24 h at the temperature of 180-200 DEG C, to obtain a Fe3O4/MoS2 material; finally, dissolving bismuth nitrate pentahydrate and ammonium metavanadate in deionized water, adding the Fe3O4/MoS2 material, mixing evenly, carrying out a reaction for 15-17 h at the temperature of 160-170 DEG C, and thus obtaining a Fe3O4/MoS2/BiVO4 composite material. When the composite material is used as a photocatalyst for treating tetracycline hydrochloride wastewater, the degradation rate can reach 90% or more, and the photocatalytic efficiency can be improved. At the same time, because of the presence of Fe3O4, the photocatalyst can be recovered more conveniently and simply for repeated experiments, the recovery cost of the photocatalyst is reduced, and the repeated utilization rate of the photocatalyst is improved.