Abstract: Tetracycline (TC), as a broad-spectrum class of antibiotics, is used in large quantities in the farming industry and has caused serious water pollution due to its characteristics of not being easily degraded naturally. In this paper, a magnetic composite Fe₃O₄-NG/PT was produced by hydrothermal method, persimmon tannin (PT) was as the matrix, and modified by nitrogen-doped graphene (NG), Fe₃O₄ was as a magnetic filler. The application of the composite in TC adsorption was also investigated. NG with its hydrophobicity and the large specific surface area made up for the lack of persistent tannin in adsorption, and Fe₃O₄ solved the problem of difficult recovery of adsorbent. The mechanism was shown by SEM, chemisorption was dominant. The adsorption isotherm is consistent with the Freundlich model, indicating that it is multilayer adsorption. The maximum capacity of adsorption at 318 K reaches 315.65 mg/g, and the adsorption efficiency reaches 94.5%. The Fe₃O₄-NG/PT composites have the advantages of large specific surface area, high porosity, and phenolic hydroxyl groups, which will broaden their application fields.