NOVELTY - An autotrophic denitrification device contains sludge hydrolysis acidification reaction vessel (1), sludge dewatering machine (2), fermentation liquid storage tank (3), raw water tank (4), and synchronous autotrophic denitrification reactor (5) in which sludge hydrolysis acidification reaction vessel is connected into sludge dewatering machine through pipeline, sludge dewatering machine outlet end is connected to fermentation liquid storage tank through pipeline, and fermentation liquid storage tank is connected to top part of synchronous autotrophic denitrification reactor through pipeline.    USE - An autotrophic denitrification device for denitrification of fermented sludge (claimed).    ADVANTAGE - Denitrification process is low-cost, simple, and easy, saves organic compound resource, and improves stability of system.    DETAILED DESCRIPTION - An autotrophic denitrification device contains sludge hydrolysis acidification reaction vessel (1), sludge dewatering machine (2), fermentation liquid storage tank (3), raw water tank (4), and synchronous autotrophic denitrification reactor (5) in which sludge hydrolysis acidification reaction vessel is connected into sludge dewatering machine through pipeline, sludge dewatering machine outlet end is connected to fermentation liquid storage tank through pipeline, fermentation liquid storage tank is connected to top part of synchronous autotrophic denitrification reactor through pipeline, top part of each pipeline is provided with peristaltic pump (12), sludge hydrolysis acidification reaction vessel is provided with stirrer (6), synchronous autotrophic denitrification reactor is provided with stirring device (7), heater (8), oxidation reduction potential (ORP) device, and pH probe (9) in which oxidation reduction potential device and pH probe are connected into automatic controller (11), and synchronous autotrophic denitrification reactor is provided into water outlet valve (13) on upper side wall of autotrophic denitrification device. An INDEPENDENT CLAIM is included for denitrification of fermented sludge which involves subjecting sludge into sludge hydrolysis acidification reaction vessel, performing anaerobic hydrolysis acidification to obtain short-chain fatty acid which is in closed condition at 25-30 degrees C for 5-7 days while stirring at 100-150 rpm in which mixed liquor suspended solids (MLSS) concentration in sludge is 12000-17000 mg/L, feeding mixture into sludge dewatering machine through pipeline which is connected to peristaltic pump, performing centrifugal sedimentation and separating fermentation broth from sludge, sending broth into fermentation liquid storage tank through pipeline which is connected to peristaltic pump, introducing nitrate wastewater into raw water tank and pumping into synchronous autotrophic denitrification reactor in which wastewater contains 20-80 mg/L compound of formula (NH4 +-N/NO3--N), stirring components, pulsed dosing broth into reactor every 20 minutes in which initial concentration of compound of (NH4 +-N/NO3--N) is 1/8-1/15 volume amount, controlling reactor temperature to 25-30 degrees C, detecting pH and oxidation reduction potential (ORP), allowing precipitation for 30-60 minutes, and discharging one half -2/3 volume amounts of supernatant liquid.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of an autotrophic denitrification device.    Sludge hydrolysis acidification reaction vessel (1)    Sludge dewatering machine (2)    Fermentation liquid storage tank (3)    Raw water tank (4)    Synchronous autotrophic denitrification reactor (5)    Stirrer (6)    Stirring device (7)    Heater (8)    Oxidation reduction potential device and pH probe (9)    Automatic controller (11)    Peristaltic pump (12)    Water outlet valve (13)