The invention discloses a sewage treatment automatic control device for reducing the production of N2O and an operation method of the sewage treatment automatic control device. The technical scheme of the invention is characterized in that the sewage treatment automatic control device for reducing the production of N2O comprises an anaerobic treatment tank, an anoxic treatment tank, an aerobic treatment tank and a sludge sedimentation tank, wherein the anoxic treatment tank is communicated with the aerobic treatment tank by virtue of an internal circulation reflux pump and a pipeline; the anaerobic treatment tank is communicated with the sludge sedimentation tank by virtue of an external circulation reflux pump and the pipeline; an anaerobic treatment tank NO2 detection probe, an anoxic treatment tank NO2 detection probe, an aerobic treatment tank NO2 detection probe, a dissolved oxygen detection probe, an auxiliary air pump, the internal circulation reflux pump and the external circulation reflux pump are respectively connected with a PLC (programmable logic controller) computer control system by virtue of conductive wires. The invention also discloses the operation method of the sewage treatment automatic control device. The sewage treatment automatic control device disclosed by the invention can be widely applied to various actual wastewater treatment processes, can be used for transforming and assembling equipment according to the actual conditions of an existing sewage plant, is simple and feasible, and is strong in operability.