The invention discloses a redundant circuit for controlling a heater in a distribution cabinet. The redundant circuit comprises a single chip, a redundant judging circuit and an OR gate circuit, wherein a control power source of the single chip is different from the control power source of the redundant judging circuit; a first output end of the single chip is connected with a first input end of the OR gate circuit; a second output end of the single chip is connected with an input end of the redundant judging circuit; an output end of the redundant judging circuit is connected with a second input end of the OR gate circuit; the output end of the OR gate circuit is connected with a relay in the distribution cabinet; the relay is used for controlling the switch-on/off of a heater loop of the heater in the distribution cabinet; if a pulse signal sent by the single chip is not received by the redundant judging circuit within 120 minutes, a high-level signal is outputted to the OR gate circuit; the heater is switched-on by switching on the relay by the OR gate circuit for a long term.