The invention relates to a preparation method and application of a graphene oxide/sodium alginate gel sphere. The preparation method comprises the following specific steps: ultrasonically dispersing graphene oxide into water to prepare a dispersion solution; adding the graphene oxide dispersion solution into a sodium alginate water solution; after carrying out high-speed stirring at room temperature, stirring at a low speed and then carrying out ultrasonic dispersion; after standing and de-foaming, finally dropwise adding into a 4 percent calcium chloride solution and carrying out crosslinking; washing with de-ionized water for 3 to 4 times to obtain a graphene oxide/sodium alginate gel sphere material; after freezing and drying, preparing a graphene oxide/sodium alginate aerogel sphere material. The preparation method is carried out under a relatively moderate condition, and the graphene oxide is packaged in a sodium alginate network structure through an ion bridge method, so that thenano toxicity of the graphene oxide is avoided; an adsorption material capable of efficiently adsorbing methylene blue in a water solution is prepared and the methylene blue is easy to separate afterbeing adsorbed; a preparation technology is simple, conditions are easy to control and the cost is low, so that the preparation method is suitable for batch production.