Abstract: Nitrogen-fixing cyanobacterium is the general name of cyanobacteria capable of fixing nitrogen and an important resource of microorganisms in the tropical and subtropical regions. A large volume of domestic and international studies have shown that it has broad application prospects in environmental protection, such as remediation of polluted environment, eco-environment monitoring and development of environment-protecting biological materials and bioenergy. Therefore, progresses achieved in the past five years (2013-2017) in the study on application of nitrogen-fixing cyanobacteria to environmental protection were reviewed comprehensively, with focus on treatment of wastewater containing high concentrations of nitrogen and phosphorus, heavy metals, arsenic, or organic pollutants, treatment of waste gas, monitoring of ecological environment, and development of biodegradable plastics, biological catalysts, and new energies, like bio-diesel, hydrocarbons and hydrogen. Moreover, its development tendency was discussed and prospected, in an attempt to provide some reference for further development of the study in this field in China.