Abstract: A transformer oil oxidation stability test bench under electric field was designed and established. Simulation tests for evaluating transformer oil oxidation stability under high voltage DC or AC field were conducted respectively for several kinds of transformer oils. Test results show that distinguished oxidation stabilities of different transformer oils under the different types of electric field can be obtained using the test bench. Transformer oils possess different oxidation stabilities under different types of electric fields. Anti-oxidation performance under DC field is better than that under AC field, while with no electric field is the best.