The invention relates to desulfurization and denitrification equipment. The desulfurization and denitrification equipment comprises an ash removal device, an oxygen regulation device, an absorption tower and an absorption liquid circulation tank, wherein the ash removal device, the oxygen regulation device and the absorption tower are sequentially communicated through a flue gas pipeline, the front end of the ash removal device is connected with a flue gas inlet, a flow regulating valve is arranged between the flue gas inlet and the ash removal device, a first temperature control device is arranged between the ash removal device and the oxygen regulation device, a second temperature control device is arranged between the oxygen regulation device and the absorption tower, an induced draft fan is arranged between the second temperature control device and the absorption tower, a first valve is arranged between the first temperature control device and the ash removal device, and the absorption liquid circulation tank is connected with the absorption tower; granular substances in the flue gas can be sufficiently separated, the moving path of the flue gas in the absorption tower is prolonged, the reaction time is prolonged, and the flue gas is subjected to sufficient desulfurization and denitrification reaction, so that the flue gas reaches the emission standard.