Aquaculture plays a significant role in promoting China′s economic development and ensuring the safety of the food supply. However, in recent years, the rapid development of China′s aquaculture industry has led to the discharge of a large amount of nitrogen-rich wastewater and pollutants every year. This has caused serious pollution in the surrounding environment and offshore areas. Regarding aquaculture wastewater, biological denitrification technology has been widely studied and applied due to its advantages in terms of green environmental protection, economic viability, and reliability. Currently, most industrial aquaculture operations rely on traditional aerobic biological treatment methods that primarily focus on removing ammonia nitrogen while often overlooking the issue of nitrate accumulation caused by nitrification. As a result, problems such as slow fish growth and decreased immunity among aquatic organisms arise. The mainstream approach of relying on periodic water exchange to reduce the presence of the three forms of nitrogen is clearly not conducive to water conservation and emission reduction. Therefore, it is necessary to pursue an economic and efficient denitrification process that can provide reliable support for the sustainable development of aquaculture in China. This paper primarily focuses on analyzing traditional denitrification methods for aquaculture wastewater and introduces the latest advancements and applications of aerobic denitrification and simultaneous nitrification and denitrification. The key influencing factors and the role of functional microbial populations are analyzed, and potential cutting-edge technologies for cost-effective nitrogen removal are discussed. This study aims to provide effective guidance for the engineering practice of biological nitrogen removal from aquaculture wastewater in China.