The invention relates to a method for removing nitrogen, and in particular relates to a method for realizing short-cut nitrogen removal from municipal domestic sewage. The invention aims to solve the problem that the prior art can not meet the requirements of the short-cut nitrogen removal process for rapid start-up and stable operation. By adopting the method, the short-cut nitrogen removal process can be rapidly and stably started up and stably operated under normal temperature. The method comprises the following operating steps: 1. preparing the activated sludge with AOB (ammonia-oxidizingbacteria) as the dominant population; and 2. realizing short-cut nitrogen removal from municipal domestic sewage by utilizing the sludge prepared in the step 1. The method has the following advantages: 1. the activated sludge with AOB as the dominant population is successfully screened under normal temperature; 2. short-cut nitrogen removal is started up by utilizing the activated sludge with AOBas the dominant population, thus achieving the aims of reducing the energy consumption and saving the investment cost; and 3. the screened activated sludge with AOB as the dominant population can ensure long-term stable operation of short-cut nitrification.