A three-section type temperature control circuit of a small-sized resistance reducing furnace includes an electric heating output network and a temperature control network which are connected with each other through a transformer, the electric heating output network is connected with a power supply and consists of a first resistive heater, a second resistive heater and a third resistive heater, and the temperature control network is connected in parallel with a first button switch and a first contactor which are connected together in series, a first opening network and a second opening network in sequence from left to right. The three-section type temperature control circuit of a small-sized resistance reducing furnace has the following beneficial effects: 1. installation is simple and can be completed only through simple wiring, and element replacement is convenient after installation is completed; 2. the three-section type temperature control circuit has functions of automatic control and manual control at the same time; 3. the reliability is high, long-time operation is allowed, and continuous working hours are equivalent to the service life; and 4. assembling cost and later-period maintenance cost are extremely low, a digital temperature control meter is low in price, and the three-section type temperature control circuit is convenient and durable.