Method and device for determining boiler operation oxygen content and automatic control system

The invention provides a method and device for determining boiler operation oxygen content and an automatic control system. The method comprises the steps that the CO concentration and NOx concentration of smoke gas in a denitration inlet at a preset operating point are obtained; the NOx concentration curve rate produced when the CO concentration in the smoke gas in the denitration inlet is smaller than a preset value is determined; according to the operation oxygen content value corresponding to the minimum value of the curve rate, the boiler operation oxygen content is determined. The optimal operation oxygen content of a low-NOx combustion boiler can be rapidly determined through the NOx concentration curve rate produced when the CO concentration in the smoke gas in the denitration inlet is smaller than the preset value, the operation oxygen content of the boiler is automatically controlled, high-efficiency combustion is ensured, and meanwhile the low-level hearth outlet NOx concentration can be kept.