Abstract: Wastewater with high salinity is widely distributed, biological nitrogen removal process is inhibited by salt when it is used to treat wastewater containing high concentration of salt and ammonium. Nitrification is the key step of biological nitrogen removal process, thus researching the effect of salinity on nitrification is significant. In this article, the research progress of the impact of salinity on wastewater biological nitrification process  was summarized. The influences of salinity stress on various aspects of nitrification process, including the efficiency of ammonia oxidation and nitrite oxidation processes, and the structure of aggregates, the characteristics of flocs and microbial community structure, were analyzed. The mechanism of nitrification process under high salinity was elaborated, providing a theoretical advice for designing biological nitrogen removal system of wastewater with high concentration of salt and ammonium.