Herein, the magnetic field facilitated electrocatalytic degradation of tetracycline is reported for the first time. A magnetic porous carbonized phthalonitrile resin electrocatalyst has been prepared through directly annealing phthalonitrile monomer, polyaniline coated barium ferrite and potassium hydroxide. The tetracycline degradation percentage (DP%) by such electrocatalyst is significantly increased up to 37.42% under magnetic field with the optimal pH value of 5.0 and bias voltage of 1.0 V (vs. SCE). The mechanism of this phenomenon is explained by the spin-selective electron removal process in the reaction between metal-oxygen species and tetracycline on the electrocatalyst. The comparison of degradation pathways for tetracycline with and without magnetic field confirms the improvement of tetracycline DP%. This work opens a new direction for the application of an external magnetic field in the electrocatalytic degradation of antibiotics in wastewater.