The invention belongs to the field of microbial fermentation and specifically relates to a high-density enriching method of an autotrophic nitrifying bacterial consortium and application of the obtained autotrophic nitrifying bacterial consortium to sewage treatment. The high-density enriching method of the autotrophic nitrifying bacterial consortium comprises the steps of inoculating thalli in anautotrophic nitrifying bacteria initial culture medium; culturing the thalli under a stirring condition by controlling the dissolved oxygen (DO) at 20-40%, at the temperature of 28-32 DEG C and the pH value of 7.5-8.0; according to a relation between NO3-N cumulated amount and inorganic carbon source consumption in the culturing process, monitoring the change of pH value in the culturing processby a pH electrode to supplement an inorganic nitrogen source and the inorganic carbon source to a culture system, and controlling the ammonia nitrogen concentration in the culturing process at 150-300mg/L; and enabling the pH value of the system to be 7.5-8.0 by the supplemented carbon source to further realize high-density automatic propagation of the autotrophic nitrifying bacterial consortium.The high-density enriching method of the autotrophic nitrifying bacterial consortium, provided by the invention, has the advantage that a problem of the consortium of poor ammonia-nitrogen treating effect caused by reasons, such as poor strain adaptation ability, added strain loss, insufficient added strain number and high cost, in the ammonia-nitrogen waste water treatment application process iseffectively solved.