Abstract: A 1.2 MeV/40 mA electron accelerator based on a single-phase transformer-rectifier without iron core and with a particle accelerating tube arranged on its axis and beam current power up to 50 kW was designed and manufactured for the radiation technology. The DC high voltage was generated by 37 cascaded full-wave, voltage-doubling rectifying circuits which were supplied by alternating voltage inducting from the primary winding exciting with 400 Hz intermediate frequency AC. The electron gun adopted an indirect heating type LaB6 as the cathode emitter and the control system was constructed by the industrial PLC. The specific features of this accelerator are compact of structure, and the energy and beam current instability are all less than ±5%. The electric power conversion efficiency is higher than 65%. It has already passed test running of 8 hours now.