This paper describes the effects of magnetic field and low pressure on dielectric breakdown of gamma-ray irradiated epoxy resin. The experiment was carried out by applying a dc pulse voltage with the intervals adjusted from 5 ms to 10 ms. The samples were irradiated in air up to 100 kGy and then up to 1000 kGy with a dose rate of 10 kGy/h by using a 60Co gamma-source. The magnetic flux density of the magnetic filed was 495 mT and the pressure was reduced to 1 kPa. The effects of the pressure, magnetic filed and gamma-ray irradiation on the time to dielectric breakdown and discharge quantity were studied. Obtained results revealed that the time to dielectric breakdown increased with increasing the total dose of radiation and was delayed by decreasing the pressure and increasing the magnetic field. The discharge quantity decreased with increasing the total dose of gamma-ray irradiation and increasing the magnetic field, but increased with decreasing the pressure.