NOVELTY - Method of cultivating ammonia-oxidizing archaebacteria involves (a) collecting mud containing ammonia-oxidizing archaebacteria and formulating into active solution; (b) preparing enrichment culture and inoculating active mud solution; (c) expanding the obtained first generation culture liquid and placing culture liquid in a incubation shaker; (d) carrying out centrifugation of the obtained culture liquid and inoculating suitable amount of active mud solution; and (e) carrying out continuous shaking of culture liquid to obtain enriched bacterial solution.    USE - The method is useful for cultivating ammonia-oxidizing archaebacteria, preferably Crenarchaeota for aerobic composting process (all claimed).    ADVANTAGE - The method increases cultivation quantity of composting archaebacteria which promotes digestion reaction and reduces the emission of nitrous oxide and loss of nitrogen.    DETAILED DESCRIPTION - Method of cultivating ammonia-oxidizing archaebacteria involves (a) collecting mud containing ammonia-oxidizing archaebacteria and formulating into active solution having density of 12200 mg/l; (b) preparing enrichment culture by taking 1 l Erlenmeyer flask and adding 500 ml enrichment culture broth and inoculating 250 ml of active mud solution obtained in step (a) and performing shake culture to obtain first generation culture liquid; (c) expanding the obtained first generation culture liquid by adjusting the pH to 6.5 and centrifuging at 30 degrees C and 140 rotations/minute and placing the expanded culture liquid in a incubation shaker; (d) carrying out centrifugation of the obtained culture liquid at 3500 rotations/minute for 20 minutes, discarding the supernatant, inoculating suitable amount of obtained active mud precipitate into a conical flask and adding 800 ml enrichment culture broth and performing shake culture to obtain second generation culture liquid, expanding the obtained second generation culture by performing the above-mentioned step (c); and (e) performing shake culture continuously for 5-8 times in an incubation shaker to obtain 800 ml enriched solution. An INDEPENDENT CLAIM is included for method of preparing the aerobic compost using ammonia-oxidizing archaebacteria which involves (a) mixing compost raw materials with 50-60% water to obtain composting mixture; (b) inoculating 5-10 l obtained ammonia-oxidizing archaebacteria for every 100 kg composting mixture obtained in step (a) to obtain fermentation mixture; and (c) performing aerobic fermentation of mixture obtained in step (b) to obtain product.