Two novel strains of cold- and salt-tolerant AOB were isolated from LEW. More than 80% of ammonia oxidation efficiency was obtained at salinity of 10‰. Two strains could achieve more than 50% NH4+-N removal at 15 °C, respectively. Two-step linear relationship was described better than one-step for NH4+-N removal. C/N and PHCs inhibit the cold- and salt-tolerant AOB activity.