Abstract: 1, 2, 5, 6-tetrabromocyclooctane (TBCO) and hexabromocyclododecane (HBCD) are both cycloaliphatic brominated flame retardants. With the ban on production and the restriction on use of HBCD, TBCO is expected to become a potential substitute, which raises concerns about its ecological and environmental impact. The properties, analytical methods, environmental behavior, and toxicological effect of TBCO are reviewed. TBCO consists of two diastereoisomers, α-TBCO and β-TBCO, of which β-TBCO has a pair of enantiomers. TBCO is usually detected by gas chromatography-mass spectrometry (GC-MS). Up to now, TBCO has been detected in air, soil, sediment, and organisms, and has shown bioaccumulation, biotoxicity, and isomer-specific biodegradation. It should be pointed out that the current limited studies on TBCO in the environment and organisms are mainly focused on aquatic ecosystems. There is very little understanding of the biological enrichment, biomagnification in the food chain, and toxicological effects of TBCO in terrestrial ecosystems. Whether TBCO has environmental persistence and long-range transport potential remains controversial. In order to comprehensively evaluate the ecological and health risks of TBCO, it is essential to explore the environmental interfacial migration, transformation, bioaccumulation and toxicological effects of TBCO, especially in the terrestrial system at the levels of diastereomer and enantiomer.