NOVELTY - The device comprises a first gas flow meter, a first valve and a first aeration head of a nitrogen machine connected with a surplus sludge fermentation reactor through an aeration pipeline. The residual sludge hydrolyzing and fermenting reactor comprises a closed tank body that is provided with a feeding pump, a mud, a first stirrer, a fermentation liquid output tube, a first electric valve, a pH sensor, a first dissolve oxygen (DO) sensor. The pH sensor is respectively connected with a pH gauge, and a first DO measuring instrument.    USE - Anaerobic sludge and low dissolved oxygen fermentation acid hydrolysis device.    ADVANTAGE - The device efficiently hydrolysis the anaerobic sludge and the low dissolved oxygen fermentation acid for long period of time.    DETAILED DESCRIPTION - The device comprises a first gas flow meter, a first valve and a first aeration head of a nitrogen machine connected with a surplus sludge fermentation reactor through an aeration pipeline. The residual sludge hydrolyzing and fermenting reactor comprises a closed tank body that is provided with a feeding pump, a mud, a first stirrer, a fermentation liquid output tube, a first electric valve, a pH sensor, a first dissolve oxygen (DO) sensor. The pH sensor is respectively connected with a pH gauge, and a first DO measuring instrument. The first electric valve is arranged on the fermentation liquor output tube. An air compressor is provided with a second gas flow meter, a second valve and a second aeration head. An aeration pipe is connected with a rest sludge acid-producing reactor. The residual sludge acid-producing reactor includes a fermentation liquid input tube that is connected with the fermentation liquor output tube. The fermenting liquid input tube is connected with the residual sludge hydrolyzing and fermenting reactor that is provided with a second stirrer, a carbon source output tube, a second electric valve, and a second DO sensor, where the second DO sensor is connected with the second DO measuring instrument. The second electric valve is arranged on a carbon source output tube. The carbon source output tube is connected with the residual sludge acid-producing reactor. A programmable process controller comprises an aeration gas relay, a sludge pump relay, a first stirrer relay, a first electric valve relay, an oxygen aerating relay, a second stirrer relay and a second electric valve relay that is respectively connected with the nitrogen machine, the feeding pump, the first stirrer, the first electric valve, the air compressor, the second stirrer, the second electric connecting valve. An INDEPENDENT CLAIM is included for a method for hydrolyzing anaerobic sludge and low dissolved oxygen fermentation acid.